Updated

Republican Sen. Ted Cruz was running into roadblocks from his own party as he tried to block the Senate from altering a bill that would strip funding for ObamaCare, with a test vote teed up for Wednesday.

Cruz is trying to preserve a House-passed bill that would defund the health care law while funding the government past Sept. 30. Cruz, however, has charted an unusual course – because he’s worried that Senate Majority Leader Harry Reid will strip the language on ObamaCare, Cruz is calling on his colleagues to block the House bill, even though he supports it.

But GOP leaders in the Senate were having none of it, and are trying to short-circuit his plan to stall the bill. They are no doubt mindful of the narrow window lawmakers have to act, with a government shutdown looming on Oct. 1 if no deal is reached.

Senate Minority Leader Mitch McConnell threw a wrench into Cruz's approach earlier Monday, saying he will not vote to block the House bill because it "defunds Obamacare and funds the government without increasing spending by a penny."

Fox News has now learned both McConnell and Minority Whip John Cornyn, R-Texas, are actively working on swaying colleagues who may be on the fence, according to sources familiar with the situation.

The move apparently came as a surprise to Cornyn's Texas colleague Cruz.

A well-placed source told Fox News that Cruz was "caught off guard" and "very upset" when he got wind of what was going on, adding he felt like he was stabbed in the back.

The Texas senator’s battle, though, had been rocky all day as he threw up a series of roadblocks only to be rebuffed by Reid.

At the same time, Reid arranged for an initial test vote Wednesday on the House passed-legislation that would avoid a partial government shutdown on Oct. 1 while simultaneously canceling funding for the health care law.

A second key vote is set for later in the week as Democrats seek to keep the health care law intact and Cruz and other Republicans resist.

Cruz told reporters he’ll do whatever it takes to prevent that outcome.

Speaking earlier on the Senate floor, he warned that any member who votes to advance the bill “will be voting to allow the majority leader to fund ObamaCare.”

“I think that vote’s a mistake,” he said. “I think that vote hurts the people of America.”

Cruz and his allies, though, face an uphill battle. To block the bill, they would have to corral 41 senators.

Reid claimed he has the votes to prevail on the health care issue.

"Any bill that de-funds Obama and his health care law is dead on arrival in the Senate," he said.

Democrats, meanwhile, have launched an aggressive campaign that seeks to pin the blame on Republicans in the event of a government shutdown. If Reid succeeds in stripping out the “defund ObamaCare” provision and sends the bill back to the House, it’s unclear whether House Speaker John Boehner would stand by the conservative wing of his caucus, or allow the bill to be called to the floor and potentially pass it with a majority of Democrats.

For its part, Obama administration spent the day warning of dire consequences unless Congress approves funding beyond the Sept. 30 end of the fiscal year.

Health and Human Services Secretary Kathleen Sebelius said Medicare beneficiaries could lose their fully-paid annual wellness doctor's visit if funding is cut off, prescription drug costs could rise, and millions of seniors who are enrolled in private Medicare coverage might be required to switch to the traditional fee-for-service coverage to continue receiving health care.

Sebelius also said federal funding for the Children's Health Insurance Program would end on Oct. 1, some Medicaid recipients would lose coverage and Indian health programs would also be affected.

Fox News' Nick Kalman and The Associated Press contributed to this report.