Democrats rode a blue wave to victory in the United States midterm elections, winning control of both chambers of Congress. Now comes the question of whether they can deliver on their promises.

The party campaigned on bringing down the cost of living, ending the war on Iran and holding President Donald Trump accountable, as well as pushing back against his immigration crackdown.

But Democrats won’t take control of Congress until January. Even then, there’s only so much they’ll be able to do without Republican cooperation.

Most bills need 60 votes to get past a filibuster in the Senate, and even if Democrats manage that, Trump can still veto their legislation. He has already threatened to do just that, telling a podcast on Monday, “I’ll veto everything.”

But the Democrats now also have other tools at their disposal, including power over Senate confirmations and control over committees that can launch investigations.

So what can Democrats realistically accomplish over the next two years, and where might they struggle to make good on their promises?

Can Democrats bring down the cost of living?

Affordability was one of the biggest issues for voters heading into Tuesday’s midterm elections, and Democrats seized on that, promising to bring down the costs of energy, housing, healthcare and groceries.

Dean Baker, an economist and cofounder of the Center for Economic and Policy Research, a US-based think tank, said one of the most effective things Democrats can do to bring down costs is push for an end to the war on Iran.

Since February, the conflict has driven up energy prices, as Iran has restricted commercial traffic through the Strait of Hormuz, a vital waterway for the oil and gas trade.

Baker argued that Democrats could use congressional investigations and oversight to pressure the Trump administration to end the war, potentially helping to give consumers relief.

Foreign policy is an area where some Republicans could find common cause with Democrats, said Baker.

Another area, he added, might be healthcare, an issue that similarly hits voters in the pocketbook.

The expiration of enhanced Affordable Care Act subsidies in 2025 has left many Americans facing higher insurance premiums.

With their new congressional majorities, Democrats could push to restore those subsidies and reverse cuts to Medicaid, the government healthcare programme for low-income Americans.

A possible path to accomplishing that goal would be to include those measures in government spending bills that Congress needs to pass, according to Baker. That would also make them harder for Trump to reject.

“Republicans living in a post-Trump world, I don’t think they want to be on the side of preventing people from getting healthcare or basically paying more for healthcare,” Baker said. “They can make the politics such that he doesn’t want to veto it.”

Trump’s tariff campaign is another factor driving up consumer costs. But Baker warned that they could be tougher to reverse, without substantial support from Republicans to override a Trump veto. Even if they do manage that, prices could take a while to actually drop.

“Prices are like rockets and feathers. They shoot up like rockets; they come down like feathers,” said Alex Jacquez, chief of policy and advocacy at Groundwork Collaborative, a progressive economic think tank.

Jacquez, however, pointed to another path Democrats could take that wouldn’t need Trump’s approval.

With majorities in Congress, Democrats could wield congressional committees to investigate companies that have been raising the prices of everything from groceries to electricity bills.

“There’s a lot of precedent for getting some real material outcomes just through having the gavels and being able to subpoena CEOs and haul people in front of Congress,” Jacquez told Al Jazeera.

While there’s no guarantee these investigations would bring down prices, they could put pressure on companies to explain or adjust their decisions.

Could a Democratic Congress hold Trump accountable?

Laura Blessing, a senior fellow at Georgetown University’s Government Affairs Institute, expects Democrats to make extensive use of their new investigative powers.

“In terms of time spent and newspaper ink spilled, this is where you’re going to see the most action from Dems, by a mile,” she told Al Jazeera in an email.

Congressional investigations do not require White House approval. But they could make life harder for Trump by scrutinising his actions both within and outside of government.

Many Democrats have signalled they plan to investigate the source of the Trump family’s wealth as part of January’s incoming Congress.

Trump’s personal wealth has soared by about $2.2bn since the start of his term, according to financial disclosure forms released earlier this year.

His family’s business empire has likewise expanded over the last two years into everything from cryptocurrency and drones to artificial intelligence and prediction markets — industries his government has favoured in its policies.

Democratic senators have already been laying the groundwork for potential investigations, sending letters to companies and government departments demanding that they preserve records.

Among the issues they could examine are whether donors to Trump’s White House ballroom received favourable treatment from the government, and whether the Justice Department targeted his political opponents.

There is no guarantee, however, that everyone will cooperate.

Trump administration officials could challenge subpoenas in court, delaying investigations. But while Blessing doesn’t expect “Trump’s nuclear family to show up to a subpoena”, she said Democrats could still question government employees and others connected to Trump’s inner circle.

Even if they uncover wrongdoing, however, there is no guarantee of legal consequences, since it’s Trump’s own Justice Department that would have to decide whether to take up the cases.

Impeachment is another possibility. Lawmakers have already introduced articles of impeachment against Defense Secretary Pete Hegseth for multiple reasons, including allegations that he waged war against Iran without seeking congressional approval first.

Republican Representative Thomas Massie has said he will try to force a House vote on Hegseth’s impeachment when the outgoing Congress returns to session next week.

Trump, who was impeached twice during his first term, however, dismissed the prospect of facing a third impeachment himself, telling reporters on Wednesday that he was “not even a little bit” worried.

“I think it would destroy the Democratic Party if they did that, because it would be impeachment for no reason,” he said.

Trump also defended Hegseth, saying he was doing “a very good job”.

Even if the House of Representatives votes to impeach a government official, the case must still be weighed in a Senate trial.

Removing an elected official would require a two-thirds vote in the Senate, meaning many Republicans would need to get on board to oust a figure like Trump or Hegseth. No president in US history has ever been removed from office as a result of an impeachment proceeding.

Could Democrats end the war on Iran?

With less than two months until the 120th Congress is sworn in, experts anticipate Trump will use his final weeks with the outgoing Republican majorities to push through any remaining legislative priorities.

It also leaves Trump a critical window in which to escalate the war on Iran, according to Trita Parsi, the executive vice president of the Quincy Institute for Responsible Statecraft, a foreign policy think tank.

“He has shown a pattern in which, in the face of humiliation and defeat, he becomes more reckless,” Parsi told Al Jazeera.

Democrats could pursue a binding resolution to wind down the war. After all, the US Constitution assigns Congress the sole authority to declare war, and laws like the War Powers Act of 1973 give lawmakers a path to ending unauthorised conflicts past the 60-day mark.

But there is no guarantee that those efforts would work, given the possibility of Trump vetoing their proposed measures.

Experts, however, say there is another way that Democrats could rein in Trump’s war powers. One of their most powerful tools will be control over government spending.

The Trump administration can continue using money already allocated for military operations, but Democrats could try to block additional funding for the war.

“It creates a limitation for how long he can pursue the war,” Parsi said. “If he needs more funding for it, we’re not talking about small sums that he can just reallocate from other places easily.”

With control of congressional committees, Democrats could also investigate the administration’s conduct during the war, including whether its military operations complied with US law.

“Rigorous oversight would not restrict military operations by itself but could raise the political costs of the war beyond what the president or other key officials are willing to endure,” said David Janovsky, a policy analyst at the Project on Government Oversight.

How much political will Democrats have to end the conflict, however, is an open question.

Blessing, the government affairs fellow, noted that the party has historically been reluctant to withhold military funding out of fear of being accused of undermining US troops.

But Parsi warned that failing to act would be politically unsustainable — and could be seen by the party’s base as a tacit endorsement of US military involvement in the Middle East.

“It will no longer be just Trump’s war,” Parsi said. “They will also co-own it, because they will be complicit, because they have the ability to stop it.”

Could Democrats rein in Trump’s immigration crackdown?

Another target for the incoming Democrat-led Congress could be Trump’s hardline immigration crackdown.

His pledge to oversee the largest mass deportation in US history has sparked widespread public backlash. A public opinion poll earlier this year found that 65 percent of Americans believe Immigration and Customs Enforcement (ICE) has “gone too far” in its efforts.

With control of both chambers of Congress, Democrats could launch investigations into ICE and other agencies involved in the crackdown.

Their probes could seek information about conditions inside detention centres, allegations of abuse and how taxpayer dollars are being used for immigration enforcement, said Heidi Altman, the vice president of policy at the National Immigration Law Center.

Altman argues Congress could also claw back the roughly $240bn already given to the Trump administration for immigration enforcement over the past two years.

That amount of money, she explained, has allowed ICE to operate with few constraints, without having to prioritise which communities to go into or who to detain.

“The only way to force a slowdown and actual sort of decision-making and prioritisation and enforcement is to dramatically curtail their budget by taking back the funding from the last session,” she said.

Doing so would require passing legislation that Trump could eventually veto. But Altman argued that Democrats should push ahead anyway.

“The worst possible thing we could do is throw up our hands and say we have limited power,” she said.

“Pass the bills, see what happens, put them on the president’s desk, and dare him to look at the American people and say he’s not signing something that they overwhelmingly demanded.”