"Even though we have made great progress addressing long-term rising health care costs with the passage of the Affordable Health Care Act, and even though the eligibility age for Social Security benefits is gradually increasing, it will do great harm to our economy and millions of seniors to raise the Medicare eligibility age or enact other significant cost-shifting alternatives," the lawmakers wrote.
House Minority Leader Nancy Pelosi (D-Calif.) was more pointed in her weekly press conference.
"Don't even think about raising the Medicare age," she said Thursday.
"We are not throwing America's seniors over the cliff to give a tax cut to the wealthiest people in America. We have clarity on that."
Proponents of raising the Medicare age from 65 to 67 say it is appropriate, giving rising life expectancy and the rapidly aging U.S. population.
Opponents argue it would raise premiums for Medicare beneficiaries and not save the federal government much money.
Thursday's letter came from, among others, Democratic Reps. Lloyd Doggett (Texas), Joe Courtney (Conn.), John Larson (Conn.), Louise Slaughter (N.Y.), John Lewis (Ga.), Jan Schakowsky (Ill.), Allyson Schwartz (Pa.), Raúl Grijalva (Ariz.), Frank Pallone (N.J.), Barney Frank (Mass.), John Tierney (Mass.), Danny Davis (Ill.), Henry Waxman (Calif.), Bobby ScottBobby ScottThe Hill's 12:30 Report A guide to the committees: House Repeal without replacement: A bad strategy for kids MORE (Va.), Kathy Castor (Fla.), Earl BlumenauerEarl BlumenauerFearing crackdown, marijuana advocates turn to Congress House Democrat introduces bill to amend presidential removal procedures Marijuana legalization grows closer with Senate tax proposal MORE (Ore.), Mel Watt (N.C.), Bill Pascrell (N.J.), Elijah Cummings (Md.), Al GreenAl GreenHouse Dems ask Fed to consider diverse candidates to fill Richmond vacancy GOP makes case for firing consumer bureau chief Dem claims, without evidence, that some Trump dossier allegations are true MORE (Texas), Janice Hahn (Calif.), Jim McDermottJim McDermottLobbying World Dem lawmaker: Israel's accusations start of 'war on the American government' Dem to Trump on House floor: ‘Stop tweeting’ MORE (Wash.), Sheila Jackson LeeSheila Jackson-LeeDem wants hearing after United passenger dragged off flight Members jam with Wynonna Judd, Keith Urban at Grammys on the Hill Dem rep: Trump WH, conservatives are attacking black women MORE (Texas), Judy Chu (Calif.), Robert Brady (Pa.), Charles Rangel (N.Y.), Gene GreenGene GreenCongress has best opportunity in years to reform fisheries management in federal waters Lobbying World A guide to the committees: House MORE (Texas), Rosa DeLauro (Conn.), Marcia FudgeMarcia FudgeDems announce 'unity commission' members If Democrats want to take back the White House start now A guide to the committees: House MORE (Ohio), Corrine BrownCorrine BrownCorruption trial could roil NJ Senate race Democrats offer double-talk on Veterans Affairs House Democrats have opportunity for redemption in selecting VA Cmte Leader MORE (Fla.), Eddie Bernice Johnson (Texas), John YarmuthJohn YarmuthTrump becomes wild card in spending fight House Democrat introduces bill to amend presidential removal procedures CBO: Budget deficits, debt to reach record highs in 30 years MORE (Ky.), Karen BassKaren BassIndependent investigation into Russian interference needed Black Dems tell Trump: ‘We have a lot to lose’ A guide to the committees: House MORE (Calif.), Brad Miller (N.C.), Peter DeFazio (Ore.), Mike Honda (Calif.), Ted Deutch (Fla.), Yvette Clarke (N.Y.), Sam FarrSam FarrMarijuana advocates to give away free joints on Capitol Hill DEA decision against reclassifying marijuana ignores public opinion 19 House Democrats' sites hacked at close of gun sit-in MORE (Calif.), Jose Serrano (N.Y.), Bennie Thompson (Miss.), Alcee Hastings (Fla.), Jim Langevin (R.I.), Keith Ellison (Minn.), Rush Holt (N.J.), Paul Tonko (N.Y.), Tim BishopTim BishopDems separated by 29 votes in NY House primary Flint residents hire first K Street firm House moves to vote on .1T package; backup plan in place MORE (N.Y.), Peter WelchPeter WelchHouse Democrats call for revoking Kushner’s security clearance Pelosi seeks to unify Dems on ObamaCare fixes Sanders says he will introduce 'Medicare for all' bill MORE (Vt.), Bill Keating (Mass.), Chellie Pingree (Maine), Colleen Hanabusa (Hawaii), Jim McGovern (Mass.), Jerrold Nadler (N.Y.), Steve Cohen (Tenn.), John Sarbanes (Md.), Linda Sanchez (Calif.), Doris Matsui (Calif.), Carolyn Maloney (N.Y.), Emanuel Cleaver (Mo.), Suzanne BonamiciSuzanne BonamiciA guide to the committees: House Liberal Dems warn against narrow focus on rural or coastal voters 'Will on the Hill' pokes fun at 2016 election MORE (Ore.), John GaramendiJohn GaramendiLawmakers sound alarm on space security North Korean tests augment calls for boosting missile defense systems Overnight Defense: Lawmakers decry proposed Coast Guard cuts | NATO defense spending increases | Drones deploy to South Korea MORE (Calif.), David Cicilline (R.I.), Donald Payne (N.J.), Jackie Speier (Calif.), Maxine Waters (Calif.), Kerry BentivolioKerry BentivolioIndiana Republican: Leaders duped me Reindeer farmer saves 'cromnibus' with yes vote High drama as .1T spending package advances by one vote MORE (Mich.), Lynn Woolsey (Calif.), Russ Carnahan (Mo.), Maurice Hinchey (N.Y.), John Olver (Mass.) and Betty Sutton (Ohio) and Del. Eleanor Holmes Norton (D-D.C.).
—This post was updated at 4:05 p.m.