WASHINGTON — A key Republican lawmaker wants to overhaul Social Security, the decades-old program that provides benefits to some 60 million retirees and disabled, with a plan to gradually increase the retirement age and slow the growth of benefits for higher-income workers.

Rep. Sam Johnson of Texas, chairman of the House Ways and Means subcommittee on Social Security, introduced legislation before the end of the congressional session last week that he said would “permanently save” the program. He said the bill would increase benefits for lower-income workers.

About 168 million people work and pay taxes toward the inevitable monthly Social Security benefits. About 42 million of the beneficiaries are retirees and their families. The trustees who oversee Social Security say it has enough money to pay full benefits until 2034, and then Social Security will collect only enough taxes to pay 79 percent of benefits.

Unless Congress acts, millions on fixed incomes would get an automatic 21 percent cut in benefits.

“Americans want, need, and deserve for us to finally come up with a solution to saving this important program,” Johnson said.

Next year, with Donald Trump as president, congressional Republicans plan to take a wrecking ball to the eight years of President Barack Obama’s policies, from the health care law to environmental regulations. Medicare, a program created under another Democrat, Lyndon B. Johnson, is in the crosshairs of Speaker Paul Ryan, R-Wis., and Trump’s pick for Health and Human Services secretary, Rep. Tom Price.

Ryan and Price favor privatizing the program, saying a voucher-system is necessary to ensure Medicare’s long-term solvency.

Johnson’s bill is designed to slow the growth of Social Security costs while boosting some minimum benefits for those who earned lower wages over longer careers. It would also limit the size of benefits for spouses and children of high-income earners, among other changes in how the benefits are calculated.

The retirement age would be gradually increased to 69, starting with those who were born in 1968 and would likely retire in the mid-2030s. Currently, individuals can receive benefits as early as age 62. The bill’s summary says the new retirement age would better reflect Americans’ longer life expectancy.