House Majority Leader Steny Hoyer (D-Md.) said Tuesday that he is “shocked” that Sen. Arlen Specter (R-Pa.) is vowing to withdraw his support for economic stimulus legislation if the final plan doesn’t mirror the Senate version of the plan.

“I’m shocked that … any Senator of any party would say, ‘This is the bill we passed, take it or leave it,’” Hoyer said. “That’s not the process.”

He was responding to Specter’s statement Monday that his support for the legislation hinges on the Senate compromise bill coming back from conference “virtually intact.”

Specter was one of three moderate Republicans who voted earlier Tuesday in favor of the Senate stimulus bill. It now heads to conference committee, where lawmakers are going to work out differences between the two chambers’ bills.

Hoyer said he remains hopeful that there is room for compromise on the bill, even though any major changes mean it could lose essential support in the Senate. He noted that the Senate bill spends about $20 billion more than the House bill and creates 500,000 fewer jobs.

“It’s not a question that they spend less. They spend more. But obviously there are differences in priorities. Those ought to be subject to discussion,” he said.

The Majority Leader expressed frustration that the fate of the multibillion-dollar package appears to lie in the hands of the three GOP Senators who supported the Senate plan: Specter and Maine Sens. Olympia Snowe and Susan Collins.

If these Senators are saying, “‘If you change anything, we’re jumping ship,’ that’s going to affect the tenor of the conference,” Hoyer said. “I would think that’s not a position we ought to be in where three people alone can decide what the Congress and the country are going to do.”

Still, while House Democrats will push for restoring their provisions in the final package, such as school construction funds, Hoyer acknowledged the bill will ultimately require the support of the GOP Senate trio. It is “a very, very tight calculus,” he said. “Are we concerned about that? Yes. Is the White House concerned about it? Yes.”

One main difference between the House and Senate bills is that the Senate plan tacks on nearly $70 billion for the alternative minimum tax. Hoyer said he doubts that provision will be stripped out.

Procedurally, the House is likely to vote on the conference report first. Hoyer said the conference committee will begin crafting a final product Tuesday, saying, “there are going to be a lot of discussions very quickly. I don’t expect a protracted conference.”