WASHINGTON — House Republican leaders struggled Tuesday to win over conservatives for a plan that would keep the government running through mid-December and force the Senate to vote on derailing implementation of President Obama’s signature health care law.

House leaders unveiled the plan to rank-and-file Republicans Tuesday but it was met with skepticism from some prominent conservatives and landed with a thud among grassroots architects of the “defund Obamacare” drive.

The GOP plan would employ an unusual procedural trick to make sure that the tea party-backed assault on Obamacare is passed by the House as part of the stopgap funding bill but is decoupled from the measure when sent to the Senate.

The plan is designed to ensure smooth passage of the funding bill before the start of the new budget year and avoid a government shutdown that could be a political disaster for Republicans if they get saddled with the blame.

“Our goal here is not to shut down the government. Our goal is to cut spending and to stop Obamacare,” House Speaker John Boehner, R-Ohio, said. “I believe that the strategy that was outlined to the members this morning accomplishes that.”

But it got poor reviews from some conservatives who see the strategy as a thinly-veiled gimmick. They want to send the legislation to block the health care law as part of a must-pass measure like the stopgap funding bill, which needs to be passed by the Democratic-led Senate and signed by the president if it is to become law.

More pragmatic Republicans see the demand to defund Obamacare as a condition for keeping the government open as a political loser. Conservative activists, however, are insistent on marrying the two issues.

Hard-line lawmakers like Rep. Thomas Massie, R-Ky., took to Twitter to denounce the idea, calling it “hocus pocus.” Rep. Steve Scalise, R-La., chairman of the influential Republican Study Committee, a group of conservatives that comprises a majority of the GOP caucus, said he couldn’t endorse the effort.

Absent a late-hour compromise on Capitol Hill, the U.S. government will run out of money to pay its debts and could begin defaulting on its obligations, piecemeal or all at once, around Oct. 18, according to a report Tuesday.