Democrats have seized on Republican proposals to limit retirement benefits to galvanize voters ahead of the midterm elections.WASHINGTON — Congressional Republicans, eyeing a midterm election victory that could hand them control of the House and the Senate, have embraced plans to reduce federal spending on Social Security and Medicare, including cutting benefits for some retirees and raising the retirement age for both safety net programs.Prominent Republicans are billing the moves as necessary to rein in government spending, which grew under both Republican and Democratic presidents in recent decades and then spiked as the Trump and Biden administrations unleashed trillions of dollars in economic relief during the pandemic.The Republican leaders who would decide what legislation the House and the Senate would consider if their party won control of Congress have not said specifically what, if anything, they would do to the programs.Yet several influential Republicans have signaled a new willingness to push for Medicare and Social Security spending cuts as part of future budget negotiations with President Biden. Their ideas include raising the age for collecting Social Security benefits to 70 from 67 and requiring many older Americans to pay higher premiums for their health coverage. The ideas are being floated as a way to narrow government spending on programs that are set to consume a growing share of the federal budget in the decades ahead.The fact that Republicans are openly talking about cutting the programs has galvanized Democrats in the final weeks of the midterm campaign. Mr. Biden has made securing Social Security and Medicare a late addition to his closing economic messaging, and Democratic candidates have barraged voters with a flurry of advertisements claiming Republicans would dismantle the programs and deny older adults benefits they have counted on for retirement.Mr. Biden has repeatedly said he will not agree to cuts to Social Security, which provides retirement and disability pay to 66 million Americans, or Medicare, which provides health insurance to about 64 million people.“You’ve been paying into Social Security your whole life. You earned it. Now these guys want to take it away,” Mr. Biden said during a visit to Hallandale Beach, Fla., on Tuesday. “Who in the hell do they think they are? Excuse my language.”The State of the 2022 Midterm ElectionsElection Day is Tuesday, Nov. 8.A Pivotal Test in Pennsylvania: A battle for blue-collar white voters is raging in President Biden’s birthplace, where Democrats have the furthest to fall and the most to gain.Governor’s Races: Democrats and Republicans are heading into the final stretch of more than a dozen competitive contests for governor. Some battleground races could also determine who controls the Senate.Biden’s Agenda at Risk: If Republicans capture one or both chambers of Congress, the president’s opportunities on several issues will shrink. Here are some major areas where the two sides would clash.Ohio Senate Race: Polls show Representative Tim Ryan competing within the margin of error against his G.O.P. opponent, J.D. Vance. Mr. Ryan said the race would be “the upset of the night,” but there is still a cold reality tilting against Democrats.Former President Barack Obama, who campaigned last week in Wisconsin for the state’s Democratic candidate for Senate, Mandela Barnes, excoriated Senator Ron Johnson, the incumbent Republican, over his plans for the legacy programs. Mr. Obama faulted Mr. Johnson for supporting tax breaks for the wealthy that were included in Republicans’ 2017 tax cut legislation, along with spending proposals that Mr. Obama said jeopardized Social Security’s future.American retirees “had long hours and sore backs and bad knees to get that Social Security,” Mr. Obama said. “And if Ron Johnson does not understand that — if he understands giving tax breaks for private planes more than he understands making sure that seniors who have worked all their lives are able to retire with dignity and respect — he’s not the person who’s thinking about you and knows you and sees you, and he should not be your senator from Wisconsin.”Mr. Johnson has proposed subjecting Social Security and Medicare to annual congressional spending bills instead of operating essentially on autopilot as they do now. That would leave the programs susceptible to Washington’s frequent and fraught debates over funding the government, making it more difficult for retirees to count on a steady stream of benefits.Still, Mr. Johnson does not hold a leadership position, and it is unclear whether his ideas — or any of the more aggressive proposals presented by those in his party — would find purchase with Republican leaders. This week, he said that Mr. Obama had “lied” about his proposal and that he had never called for Social Security cuts.Mr. Biden and other Democrats have also criticized a plan from Senator Rick Scott of Florida, the chairman of the Senate Republicans’ campaign arm, who has proposed subjecting nearly all federal spending programs to a renewal vote every year. Like Mr. Johnson’s plan, that would make Medicare and Social Security more vulnerable to budget cuts.Senator Mitch McConnell of Kentucky, the Republican leader, said this year that a bill to sunset those programs every five years “will not be part of a Republican Senate majority agenda.”Still, the fact that key Republicans are openly broaching spending cuts to Social Security and Medicare — or declining to rule them out — is a break from former President Donald J. Trump, who campaigned on a promise to leave the programs intact.With President Biden in the White House, Republicans have little chance of securing changes to Medicare or Social Security.Tom Brenner for The New York TimesSeveral conservative Republicans vying to lead key economic committees in the House have suggested publicly that they would back efforts to change eligibility for the safety net programs. The conservative Republican Study Committee in the House, which is poised to assume a position of influence if the party claims the majority, has issued a detailed plan that would raise the retirement age for both programs and reduce Social Security benefits for some higher-earning retirees. The plan would increase premiums for many older adults and create a new marketplace where a government Medicare plan competes with a private alternative, in what many Democrats call partial privatization of the program.Representative Kevin McCarthy of California, who is in line to be House speaker if his party wins control, told Punchbowl News last month he would not “predetermine” whether Social Security and Medicare cuts would be part of debt-limit negotiations. Those comments suggested that, unlike in past negotiations, Republicans could demand future cuts to the programs in order to raise America’s borrowing limit and avoid a default on government debt. Mr. McCarthy later told CNBC that he had not brought up the programs and was committed to “strengthening” them, though he did not provide details.Asked whether Mr. McConnell would support any changes to the programs should Republicans capture the majority, aides pointed only to his specific comments about Mr. Scott’s plan.With Mr. Biden in the White House, Republicans have little chance of securing changes to either program.Democratic candidates and outside groups supporting them have spent $100 million nationwide this election cycle on ads mentioning Social Security or Medicare, according to data from AdImpact. Nearly half of that spending has come since the start of October.“Far-right extremists are gutting retirement benefits,” a narrator says in an advertisement targeting Cassy Garcia, a Republican seeking to unseat Representative Henry Cuellar, a Democrat, in a fiercely contested Texas district. “They’ll slash Medicare and Social Security — benefits we paid for with every paycheck.”Republicans have campaigned far less on the programs, spending about $12 million this cycle on ads mentioning them. Republican candidates have largely embraced repealing the Inflation Reduction Act, which Mr. Biden signed in August and which reduces prescription drug costs for seniors on Medicare. Some candidates have begun pushing back against Democratic attacks about Social Security and Medicare.In a recent ad, Don Bolduc, a Republican challenging Senator Maggie Hassan, Democrat of New Hampshire, says he will not “cut Social Security and Medicare for older Americans,” though it remains unclear if he would reduce benefits for future retirees. Mr. Bolduc spoke in favor of privatizing Medicare in August, Politico reported this fall.Democrats and Republicans largely agree Congress will need to ensure the solvency of the programs in the decade to come. Spending for the programs is projected to balloon in the coming decade as more baby boomers retire. The trustees of the Social Security and Medicare trust funds estimate that a key Medicare trust fund will run out of money in 2028 and the main Social Security Trust Fund will be insolvent in 2034, potentially forcing cuts in benefits if Congress does not act to avoid them.In the 2020 campaign, Mr. Biden proposed raising payroll taxes on high earners to help fund Social Security, while also making the program’s benefits more generous for many workers. He put that plan on the back burner in his first two years in office, as he pushed a sweeping economic agenda that included new spending on infrastructure, low-emission energy, health care and advanced manufacturing. Republicans largely oppose Mr. Biden’s tax increases.Fiscal hawks said this week that Mr. Biden’s attempts to wield Social Security and Medicare against Republicans in the midterms would only set back efforts to shore up the programs.“This is clearly election-time pot stirring,” said Maya MacGuineas, the president of the Committee for a Responsible Federal Budget in Washington. “Changes desperately need to be made to the programs to ensure solvency — politicians can disagree about what changes to make, but not whether they need to be made. It’s highly disappointing to hear the president, who knows better, resort to fearmongering rather than using his platform to help enact needed changes.”Emily Cochrane More