House Republicans offer short-term debt ceiling extension (VIDEO)

In a significant shift in strategy, House Republicans unveiled a plan Thursday to extend the US government's ability to borrow money for six weeks if President Barack Obama agrees to new negotiations on spending cuts.

The plan would not end the partial government shutdown, now in its second week.

White House spokesman Jay Carney said Obama "would likely sign" a clean debt ceiling extension plan.

But he dodged repeated questions about whether Obama would agree to negotiations with Republicans if the shutdown continues.

The president was "happy that cooler heads at least seem to be prevailing in the House," according to Carney.

The offer to raise the debt ceiling is a significant shift for Republicans, who had hoped to extract concessions on spending and Obama's health care reform law. By extending the government's borrowing authority through December, it would eliminate the near-term threat of a default that would hit everyone from retirees to bondholders.

"It's time for these negotiations and this conversation to begin," House Speaker John Boehner told reporters after presenting the plan to his fellow Republicans.

Pundits said the plan is no slam-dunk, and it's already facing some opposition and skepticism among other House Republicans.

“I’m looking for something that shows we’re recognizing the problem facing America because of our debt and we’re going to address it,” Rep. Mo Brooks, R-Ala., told Politico.

Senate Majority Leader Harry Reid responded to the debt ceiling offer with, "Let's wait and see what the House does."

However, on negotiating before the government reopened, Reid said, "Not going to happen."

Still, investors seemed to be heartened by the development. US stocks rallied strongly, with major indexes climbing more than 1 percent.

GOP leaders planned to meet with Obama at the White House later Thursday afternoon.

Thomson Reuters contributed to this report.