Sen. Mike Lee is leading an effort to block legislation that would continue funding for the federal the government unless money for the new health care law is stripped from it.

Lee, R-Utah, told the Washington Examiner he and fellow Senate Republicans will write to Majority Leader Harry Reid, D-Nev., warning that they will oppose upcoming legislation to fund the federal budget unless it excludes money for the implementation or enforcement of the health care law.

“This is our last point of leverage,” Lee said, pointing out that implementation of Obamacare is set to begin in 2014.

The move could set up a partisan showdown over keeping the government up and running. Funding runs out Sept. 30, the end of the fiscal year, and Congress must pass a stopgap measure known as a continuing resolution, or CR, by then to continue funding for government agencies and programs.

Lee said 15 Republicans have signed his letter and he expects the number will grow. He said 65 House Republicans have also pledged their support for the effort.

Senate Minority Leader Mitch McConnell, R-Ky., has not signed the letter. The No. 2 and No. 3 GOP leaders, Sens. John Cornyn, of Texas, and John Thune, of South Dakota, have signed it, as has Sen. Marco Rubio, of Florida.

It’s likely the CR would require 60 votes to pass the Senate. Democrats control 55 votes, so Republicans would need at least 41 members to vote against the CR to block it, a potentially politically risky move because the party could be blamed for a government shutdown.

Republicans have been buoyed in their efforts to stop implementation of the health care law since President Obama moved earlier this month to delay implementation of the employer mandate by one year. Since then, the House has voted for a one-year delay in both the employer and individual mandates.

Lee said the pressure would be on Democrats, not Republicans, to keep the government running by extracting the funds for the health care law.

“We are not for a government shutdown,” Lee said. “We don’t want that, nor do we think Harry Reid would take the government into a shutdown posture just to defend a law that the president has already told us is not ready to be implemented.”

Neither Reid nor House Minority Leader Nancy Pelosi, D-Calif., responded to a request for a comment.

The other signers of Lee’s letter are Sens. Ted Cruz, of Texas; Jim Risch, of Idaho; James Inhofe, of Oklahoma; David Vitter, of Louisiana; Roger Wicker, of Mississippi; Mark Kirk, of Illinois; Jeffrey Chiesa, of New Jersey; Mike Enzi of Wyoming; Deb Fischer, of Nebraska; and Charles Grassley, of Iowa.