WASHINGTON — Republican presidential contender Scott Walker on Tuesday unveiled his health care plan: Repeal Obamacare and replace it with age-based tax credits that Americans could use to offset the cost of purchasing their own coverage.

Under his plan, the Wisconsin governor said he would give up to $3,000 directly to taxpayers to buy health insurance. The amount would range from $3,000 in credits for those aged 50 to 64 and scale down to $900 for those age 17 and under, and go to those without health insurance from their jobs.

Walker also backed long-standing Republican health proposals to allow consumers to purchase insurance out-of-state, loosen restrictions on health savings accounts and reform medical malpractice lawsuits.

“This gives them a way to get an affordable health care plan,” he said in a speech in Minnesota, highlighting the plan’s tax credits.

Republicans have long vowed to repeal President Barack Obama’s signature 2010 health care law, commonly known as Obamacare. While most of the 17 Republican presidential candidates have echoed that pledge, few have offered detailed alternatives.

Under the law, consumers who do not get health insurance from their employer or government programs such as Medicare and Medicaid can buy it under federal or state-run insurance exchanges. Those who qualify receive a subsidy to offset the costs.

Walker criticized that system and the role of the Internal Revenue Service in overseeing the subsidies.

“Unlike Obamacare policies that give subsidies to insurance companies, these tax credits belong to consumers,” Walker wrote in his plan, released on his website.

He said consumers should be able to buy health insurance across state lines, although it was not immediately clear where consumers would buy it or what would happen to the current exchanges.

Additionally, Walker called for overhauling Medicaid, the federal-state health insurance program for the poor, through block grants and other changes.

U.S. Sen. Marco Rubio of Florida, another contender for the Republican presidential nomination in the November 2016 election, also has called for health care changes. In an opinion piece in Politico late Monday, he reiterated his promise to seek tax credits for Americans who buy their own health insurance but offered few new details.

Another candidate, Louisiana Gov. Bobby Jindal, who laid out his health care policy ideas last year, criticized Walker’s plan. He said Walker was accepting the premise of Obamacare and “merely quibbling over the details.”