WASHINGTON — Congressional Republicans are planning to start the new year with another attempt to ban federal funds for Planned Parenthood. But after five years of fruitless legislative attacks, the House vote next week is likely to be the last, conservative activists say, until a Republican moves into the White House.

That pragmatic resignation is remarkable given the intensity that conservative lawmakers and advocacy groups brought to the issue last summer and fall, when abortion opponents began releasing videos indicating that Planned Parenthood sells fetal tissue to researchers for profit, which Planned Parenthood denies. Conservatives threatened to shut down the government over payments to the nonprofit group and forced John A. Boehner from the speakership when he shied from a showdown with President Obama.

Yet this month, many of these hard-line Republicans, including several who are running for president, were all but silent as Congress passed an annual government spending bill that would maintain about $500 million in Medicaid reimbursements for the network’s health services to low-income people. (Federal law prohibits funds for most abortions.)

The anticlimactic outcome — and the potential cease-fire ahead — stem from a confluence of factors: a conservative honeymoon with the new speaker, Representative Paul D. Ryan of Wisconsin; a tactical split among abortion opponents; and lawmakers’ old-fashioned desire to get home for the holidays.