Democrats can use their new majorities to block Donald Trump’s agenda through the power of the purse. With the current funding resolution expiring on December 11, the party has leverage to limit spending on vanity projects and the Iran war. They also plan to investigate corruption and protect healthcare funding.

Through using their strengths on spending, they can stymie and reverse much of Trump's agenda

The writer is co-editor of The American Prospect and author of 'Notes for Next Time: Surviving Tyranny, Redeeming America'

Despite their new House and Senate majorities, some argue that Democrats will struggle to accomplish much because the party is too internally divided, President Donald Trump retains all the powers of the executive and it takes two-thirds of both Houses to override a Trump veto.

Such arguments are misplaced. Under the Constitution, Congress has the power of the purse. Even during the so-called lame-duck session, when the outgoing Congress meets for the last time, Democrats will enjoy new power to stymie Trump.

When Congress recessed in September, neither House nor Senate had approved Trump's unprecedented $1.5tn defence bill to support the failed Iran war and far-fetched projects such as a "Golden Dome" missile defence system and a new "Trump class" of battleships. Nor had Congress passed any of the 12 normal appropriations bills for this fiscal year.

When appropriations are late, Congress passes a short-term continuing resolution. Otherwise, the government shuts down. The current resolution expires on December 11.

Republicans still possess the power that comes with the narrow majorities they retain in both Houses until January. But because they know that Democrats will have a lot more votes in the new Congress, the Democrats have new leverage to set terms, even in the lame-duck session.

As the price of passing a new continuing resolution, Democrats hope to put limits on the Iran war, to prohibit vanity projects like Trump's triumphal arch, and to compel the president to use duly authorised funds that he has refused to spend despite a 1974 law banning such impoundment.

In the new Congress, Democrats plan detailed investigations of everything from presidential corruption to Trump's warm relationship with Vladimir Putin to the economic consequences of the Iran war. They will pass some legislation in the spirit of setting an agenda for 2028, knowing that Trump will veto it. But other legislation may get enough Republican support to override a veto or to compel the president to sign. These include popular measures such as reversing Trump's brutal cuts in funding for Medicaid and for insurance subsidies under the Affordable Care Act. Both hit Republican constituents just as hard as Democratic ones.

Another example is tariffs where Congress could drastically curb presidential power -- a move numerous Republicans would also support. Indeed, Republicans who survived the midterm Democratic wave, mindful of Trump's monumental unpopularity, may be looking for ways to distance themselves from him.

Here again, the power the purse is paramount. The final stage in Congressional approval of the budget is a process called "reconciliation", in which the budgets passed by the House and Senate must be reconciled. Unlike ordinary legislation, reconciliation is exempt from the Senate filibuster, which requires a 60-vote supermajority to overcome. It can be passed with an ordinary majority of 51 votes, and Democrats will have at least 54.

Democrats could use reconciliation to constrain Trump's spending in multiple respects, and to mandate spending in others, as well as limiting abuses by agencies such as ICE, the Department of Health and Human Services under Robert F Kennedy Jr and the Pentagon under Pete Hegseth (if he has not been impeached.) They could also compel Trump to restore funding for the National Institutes of Health and for climate research.

While there are some differences around the edges -- ceasing all aid to Israel, abolishing ICE -- the vast majority of Democrats in both houses are mainstream progressives on the pocketbook issues that propelled the blue wave. And they are aware of the opportunity that history has delivered.

James Talarico, the newly elected Democratic senator from Texas, said it as well as anyone in his victory speech: "The real fight in this country is not left versus right. It is top versus bottom . . . The people at the top divide us by party, by race, by gender, by religion, by culture, so we don't notice that they are picking our pockets."

This framing unites Democrats and speaks to the lived grievances of citizens. Trump's new chief of staff, Stephen Miller, who epitomises the president's excesses, will only help mobilise the opposition. The last time a determined Democratic Congress went up against a discredited Republican president was in 1974. It didn't end well for Richard Nixon.