WASHINGTON — Out of power, disorganized and stung by their November election losses, Democrats have struggled to mount a coherent response to President Donald Trump as he has unleashed a blitz of contentious nominations, explosive executive orders and an unforeseen rampage by Elon Musk and his acolytes through the executive branch.

Now, with Congress returning from its spring recess this week and Republicans under pressure to deliver on a legislative agenda, Democrats believe they have a prime opportunity for a reset. Republicans will be forced to begin providing politically charged specifics of their tax and spending program, handing the minority ample fodder for attacks.

House Republicans have so far been able to generalize about their spending plans in the budget outline that they barely squeezed through the House and Senate. But beginning this week in multiple House committees, lawmakers will have to explain in public how they would achieve $1.5 trillion or more in savings to go with hundreds of billions of dollars in new spending on the military and border enforcement, and trillions in tax cuts.

“Up to this point, Republicans have been lying about their intentions,” Rep. Hakeem Jeffries of New York, the House Democratic leader, said in an interview. “As we move forward with the next phase of the budget process, it will become crystal clear in committee after committee the damage they are trying to do to the American people.”

Democrats say no cut is too small to highlight. They intend to focus on the consequences of the GOP plan, from reducing food assistance for the poor to eliminating tax credits on clean energy. They plan to call special attention to possible Medicaid cuts, an issue they have raised repeatedly in recent months.

Republicans have insisted that their legislation will not eliminate health insurance or other benefits for those who need them, including Medicaid coverage. Multiple GOP members of the House and Senate have said that they would not support any final package that slashes Medicaid.

But Democrats and independent budget analysts say that if Republicans have any hope of meeting their budget targets, they will have to wring significant savings out of the joint federal-state program for low-income Americans.

Democrats, who have spent part of the recess plotting strategy for the committee sessions, say they realized Medicaid was a political soft spot for Republicans in January, when the Trump administration briefly froze a portal used to fund state programs, drawing an intense backlash from lawmakers and state officials. They have since focused on the likelihood of GOP cuts, putting Republicans on notice about the political risks.

Republicans have floated options for reducing the cost of the program without cutting benefits, including by instituting work requirements and clearing the Medicaid rolls of immigrants living in the country illegally. Rep. Austin Scott, R-Ga., suggested another approach in a recent Fox Business Channel interview, saying the Republican-led Congress could cut the amount that the federal government reimburses states for people enrolled in the Affordable Care Act’s adult expansion group in Medicaid.

“Nobody would be kicked off of Medicaid as long as the governors decided that they wanted to continue to fund the program,” he said, implying that any cuts should then be attributed to the states, not Washington.

But Democrats will frame that as a cut. And they have pledged to hold the Republicans accountable as the legislation comes together.

“As Republicans flesh out the details of their massive tax giveaway for billionaires, people will not have to wait to learn what’s on the chopping block,” Sen. Chuck Schumer, D-N.Y., the minority leader, said in a statement. “Democrats are going to make sure everyone knows every detail of who is really on the losing end of Donald Trump’s deal.”

Derailing the Republican legislation will be difficult. Despite serious differences between the House and the Senate, as well as disagreements among Republicans in both chambers, congressional Republicans — with help from Trump — have managed to move the process forward.

But the coming debate will be their most difficult yet.

Democrats are returning to Washington sensing that they are on better footing after an extremely difficult start to the year, when they looked for ways to stand up to Trump as he flexed his popularity and his willingness to work around Congress.

They may have hit a low point in mid-March, when they engaged in a nasty internal quarrel over whether a group of Senate Democrats led by Schumer should have provided the votes for a six-month government funding bill. They have been eager to pivot and take on the other party.

During the recess, Democrats appeared in Republican-led states and House districts to build opposition to the coming legislation, focusing daylong programs on preserving Social Security and Medicaid. Trump has helped them regroup with on-again, off-again tariffs that have rattled the markets and cut into retirement savings.

The Musk-led reductions in the federal workforce have spurred concern that government services could suffer, particularly with cuts at Social Security offices and veterans facilities. The drop in the president’s approval rating has not gone unnoticed by Democrats.