A coalition of conservative groups are planning to pressure Congressional Republicans during the summer recess to sign on to a measure to defund President Obama’s healthcare law.

The Club for Growth, Freedom Works, Tea Party Patriots and For America joined Republican Sens. Marco Rubio, Mike Lee and Ted Cruz for a press conference on the Hill Thursday to continue to make the case against voting for funding the government if it includes money to implement Obamacare. While the lawmakers were content to criticize the law, the organizations put it in much more blunt terms: you’re either with us or against us.

“If you fund Obamacare, you own Obamacare,” said Brent Bozell, chairman of For America.

That means Republican senators who have yet to sign onto the effort can expect to hear an earful from activists during the next five weeks when lawmakers go back to their states. And if they don’t eventually join the fight when Congress returns in September to take up its fiscal battles, the conservative leaders vowed to fund any primary opposition that emerges.

As a signal to Republicans, Freedom Works said it is doubling the weight on this decision in their rankings of lawmakers’ voting records. President Matt Kibbe said their organization bombarded Republican Sen. John Cornyn’s Texas office with phone calls and emails after he backed off joining Rubio, Lee and Cruz.

“Cornyn is the test case,” Kibbe said. “We’ll take that same enthusiasm into town halls and other districts.”

Unlike the 40 efforts in the House to repeal Obamacare — ” a symbolic vote, which we’ve had far too many of,” Cruz said — Cruz, of Texas, said conservatives see the defund effort as “the single best time to kill Obamacare.”

Rubio, R-Fla., also signaled an unwillingness by to work with Democrats to improve the law once it is implemented, something Obama has asked for.

“I don’t think it can be fixed,” Rubio said.