Top House Republican leaders Thursday rejected the short-term spending plan expected to be passed by the Senate in coming days, increasing the possibility of a government shutdown next week.

Asked if the House would pass the bill unchanged once it is sent from the Senate, Speaker John A. Boehner (R-Ohio) replied: “I do not see that happening.”

Using Senate rules permitting him to change the wording of a spending measure approved by the House last week, Majority Leader Harry M. Reid (D-Nev.) is expected to strip out language that would defund the law, change the expiration date on the funding bill to Nov. 15, and pass the measure with a simple majority achieved entirely with Democratic votes.

Once the bill returns to the House, any move to change it would by necessity mean that the fight over funding the government would almost certainly continue at least until the final minutes of the fiscal year late on Monday night since the Senate’s arcane, time-sensitive rules would make swift consideration unlikely.

Boehner’s tough words on the spending bill came as he and his lieutenants were still working to find a way past the immediate crisis by shifting their attention to the next fight over raising the nation’s debt ceiling. The Treasury Department said Wednesday that the nation is likely to exceed its borrowing authority on Oct. 17 — meaning an even more nerve-wracking deadline is just around the corner.

Countdown to the (possible) shutdown

In response, House Republicans were working to unveil a bill that would tie an increase in the nation’s borrowing limit to a wish list of conservative priorities, including a one-year delay of the implementation of Obamacare. The bill was intended as a way to avert the shutdown by becoming the new weapon for continuing the assault on Obamacare, allowing Republicans to abandon the fight against the clean government funding bill that the Senate will pass.

By late Thursday afternoon, however, Boehner had convened his leadership team in the speaker’s office to try to hash out the next strategic steps amid signs of trouble in rounding up enough votes to pass the new GOP debt ceiling bill. It was not clear Boehner will be able to get the support from conservatives needed to pass that bill before the deadline for the continuing resolution.

GOP leaders began outlining their debt ceiling proposal at the weekly closed-door meeting with rank-and-file Republicans.

But speaking Thursday at Prince George’s Community College in Largo, Md., Obama warned that he will not accept delays to the health-care program’s taxes, mandates and benefits in return for raising the debt ceiling next month. He said Republicans “have just spun themselves up over this issue.”

“The closer we’ve gotten to this date, the more irresponsible people opposed to this law have become,” Obama said, referring to the Oct. 1 start of enrollment in the program’s new health-insurance plans.

“The Affordable Care Act is here to stay,” Obama said, stressing that he would not negotiate delays or other changes to the law as part of budget talks or the debt-ceiling process.

“No Congress before this one has ever — ever — in history been irresponsible enough to threaten default,” Obama said. The tactic amounts to an effort to “blackmail a president for concessions,” he said, adding: “I will not negotiate on anything when it comes to the full faith and credit of the United States of America.”

If conservatives are swayed by the proposal to use the debt ceiling instead of the short-term spending bill to fight over the health-care law, they might consent to quickly pass a spending plan that would keep the government chugging next week.

Thursday morning, Boehner refused to outline what Republicans will attach to the spending bill, formally known as a continuing resolution, when it arrives from the Senate.

“We’re not going to have a discussion about the CR — speculate about the CR — until the Senate sends us their bill,” he told reporters.

Two hours after Boehner’s announcement, Reid said the Senate would not accept another House-passed funding resolution with different legislative strings attached to it.

“They keep digging, deeper and deeper,” the Senate majority leader told reporters as a countdown clock ticked away the days, hours, minutes and seconds to Monday night’s shutdown deadline.

Sen. Barbara Mikulski (D-Md.), chairman of the Senate Appropriations Committee, rejected any proposal to rein in Obamacare in either the government funding bill or the debt ceiling.

“You can huff, you can puff for 21 hours, but you cannot blow the Affordable Care Act away,” she said, referring to the filibuster-like speech of Sen. Ted Cruz (R-Tex.) that ended Wednesday at noon.

If conservatives are swayed by the proposal to fight their health-care battle over the debt ceiling rather than the short-term spending plan, they might consent to allow a clean plan to allow the government to keep chugging next week despite Boehner’s tough words.

Those tricky internal GOP discussions will continue over the next several days. Boehner continued to maintain, however, that Republicans do not want the government to shut down and are looking for ways to avoid that outcome.

“The American people don’t want the president’s health-care bill,” he said. “And they don’t want the government to shut down. The Republicans are listening.” He said the House spending plan, soon to be amended by the Senate, accomplished both goals.

Boehner was responding to the continued insistence of the most conservative members of his conference, who believe that the spending bill cannot be passed without first defunding Obamacare.

“With October 1 four days away from submission to Obamacare, I think now is the right time to protect everybody and not wait until later,” said Rep. Tom Graves (R-Ga.), a key conservative advocate for undoing the health-care law.

The House GOP proposal to raise the debt ceiling would delay implementation of the health-care law for one year, it would establish a timetable for tax reform, squeeze $120 billion from federal health programs over the next decade — in part by tightening medical malpractice laws — and cut federal civil service pensions.

The measure also would approve construction of the Keystone XL oil pipeline and advance other GOP economic goals, including increasing offshore oil drilling, blocking federal regulation of greenhouse gas emissions and restricting most forms of federal industry regulation.

About the only major piece of the Republican agenda missing from the bill is a ban on late-term abortions — and some lawmakers who oppose abortion were arguing to add that, GOP aides said.

By stuffing the bill with so many appealing provisions, GOP leaders hoped to persuade at least 217 Republicans to support its sole negative aspect: raising the $16.7 trillion federal debt limit through Dec. 31, 2014 — an increase worth about $1.1 trillion, by independent estimates.

Rep. Pete Sessions (R-Tex.), a key leadership lieutenant, said he was “very confident” that rank-and-file Republicans would support the debt-limit package.

“They’re telling us to be flexible” on the debt limit, Rep. Mo Brooks (R-Ala.) said after learning about the plan Thursday morning at the closed-door GOP conference meeting.

Brooks said he was still undecided about how to proceed but doubted that the plan has sufficient Republican support.

“It definitely has a lot of goodies in it, things that arguably would grow the economy and arguably would generate more revenue. But still you have to address the problem,” he said.