House Republicans last month rallied behind President Bush’s vow to restrain spending with a pledge of support from enough lawmakers to uphold vetoes of appropriations bills.

But some of the 147 GOP lawmakers who signed that pledge now say they won’t necessarily stand behind it. It’s a sign that although Republicans are rhetorically backing the president’s efforts to challenge Democrats on spending, the details of the fight could prove uncomfortable for some GOP members, particularly those who face tough re-election contests next year.

“I’m boxing myself in, in a very strange way, and I have to figure it out,” said Christopher Shays of Connecticut, the only House Republican from New England to survive the 2006 election. “I’m going to re-look at the letter I signed and may have to go down to the White House and say I’m not on board.”

So far, the House has considered four fiscal 2008 spending bills that the president has threatened to veto over cost: Energy-Water (HR 2641), Homeland Security (HR 2638), Interior-Environment (HR 2643) and Labor-HHS-Education (HR 3043). Overall, 63 lawmakers who signed the pledge have voted for at least one of those bills.

Four House Republicans — Shays, Wayne T. Gilchrest of Maryland, Steven C. LaTourette of Ohio and Mike D. Rogers of Alabama — who signed the letter nonetheless have voted to pass all four bills.

It takes a two-thirds vote to override a veto. If all 435 House seats are filled, it would require 146 votes to sustain a veto.

So far, only the Energy-Water bill (HR 2641) passed the House by a “veto proof” margin — 312 to 112. The bill is popular because it funds local Army Corps of Engineers projects.

The vote on Labor-HHS-Education bill, 276-140, was close, but enough GOP members who have voted against spending measures missed the vote that a veto likely could be sustained.

Senate Majority Leader Harry Reid of Nevada and House Speaker Nancy Pelosi of California on July 20 wrote Bush to request a meeting “to see if we can reach agreement on . . . appropriations issues and avoid a protracted battle over relatively small differences.”

In the end, the Senate may save House GOP members from a veto fight with their president. The Senate has yet to pass a single appropriations bill. Several House members said they think that means it’s increasingly likely that Congress will send the president a multibill “omnibus” spending package this fall. That would focus a veto showdown more on overall spending than on individual bills.

“That’s probably where we’re headed,” LaTourette said of an omnibus.

The votes on appropriations bills so far don’t appear to worry House GOP leaders or the White House. “We’re confident that in the end, the Republicans will see eye to eye with the president on overall spending levels and the Democrats’ tax-and-spend policies,” said a spokesman for the White House Office of Management and Budget.

The House GOP letter pledging to uphold spending bill vetoes was circulated last month by members of the conservative Republican Study Committee (RSC). Their leaders emphasized that those signing it agreed to sustain vetoes, not necessarily to vote against bills as they advance through the House.

John Campbell, R-Calif., the RSC’s budget chief, said, “A number of people told me they might vote for some on the way out but would vote to support the veto.” Several members who voted for bills but signed the pledge said that is their position.

“I would support any veto by the president,” said GOP appropriator Harold Rogers of Kentucky, who voted for the Homeland Security and Energy-Water bills.

Congress adopted a budget (S Con Res 21) earlier this year that calls for $23 billion more in fiscal 2008 discretionary spending than the $933 billion the president requested.

The GOP lawmakers’ letter to the White House is clear about its intent. “Like you, we oppose the large overall increase in federal spending contained in the fiscal year 2008 budget resolution,” it said.

But some GOP lawmakers said they believe they have flexibility. “The letter is a marker, it sets a tone, but the letter in my judgment does not draw a line in the sand,” Gilchrest said.

Roger Wicker, R-Miss., who voted for the Energy-Water bill, said, “My signature on that letter was a statement of general principle.”

House GOP appropriator Ray LaHood of Illinois signed the pledge and has voted for three of the bills. “If I’m asked, I’ll make the case some bills shouldn’t be vetoed,” he said. When asked whether he would support vetoes of bills he voted for, LaHood said, “I would want to see what his message is and how much heartburn they have over it.”

Zach Wamp, R-Tenn., said that although he is generally supportive of Bush’s stance on spending, he made clear to the president when Bush met with GOP members of the House Appropriations panel last month that he would break ranks on the Energy-Water measure.

“I told him face to face I would be voting for that bill,” Wamp said.