WASHINGTON — Washington state wrung a promise of $220 million from Congress to replace the Alaskan Way Viaduct yesterday, but lawmakers warned the money could disappear if voters approve a popular anti-gas-tax initiative this fall.

And the amount contained in the long-term transportation-funding bill being finalized in Congress is about a fifth of the $1 billion Seattle's mayor once requested to help replace the aging viaduct.

Still, the state's congressional delegation celebrated its bipartisan efforts after the money was approved yesterday by the joint House-Senate committee that reconciled competing versions of the bill.

The bill now goes back to the House and Senate for final votes, expected by today.

"This is a significant victory," said Sen. Patty Murray, a Democrat, adding that the amount was "substantially lower than what we had hoped it to be."

But Murray warned: "Everybody needs to understand that if the gas tax is repealed in November we will lose the federal dollars that have been allocated."

An initiative to repeal the 9.5-cent-a-gallon gas tax approved by the state Legislature this year is expected to be certified for the ballot. The first increase, of 3 cents, went into effect July 1.

The architects of the tax-repeal initiative have said they aren't trying to stop transportation improvements. But they want the state to focus on relieving traffic congestion and on restoring accountability for how the tax dollars are spent.

The federal transportation bill provides more than $286 billion to states for highway and other projects through the end of the decade.

Rep. Dave Reichert, R-Auburn, was the state's only representative on the joint committee to hammer out the spending package. He praised Rep. Don Young, R-Alaska, the powerful chairman of the House Transportation Committee, as key to getting viaduct money.

"It was only in the last two days that the final figures took shape," Reichert said. "I told Young, 'It's coming together,' and he said, 'Shh! Don't jinx me.' "

Young said, "This is a critical piece of legislation. Dave lobbied hard for his region's concerns and even brought me out to Washington to take a look at not only his district, but the surrounding area's transportation concerns."

In late June, Young quietly toured the viaduct, and told Reichert "that thing's a wreck."

The viaduct was damaged in the 2001 Nisqually earthquake, and officials say another strong jolt could force them to close the elevated roadway.

In an interview after his trip, Young expressed his concerns about the cost of Mayor Greg Nickels' plan to replace the viaduct with a tunnel. Young said Congress would find a little money to help re-build the viaduct, but a tunnel would find no patrons in D.C.

That left Nickels worried that debate over the tunnel would keep Young from finding any money to help replace the viaduct, Reichert said. The mayor asked Reichert to arrange a private meeting with Young.

Young and Nickels ended up chatting by phone on July 14. The next day, the mayor's spokeswoman, Marianne Bichsel, said only that Nickels "described it to me as a very good conversation. Very positive."

Nickels couldn't be reached for comment.

Yesterday, everyone played up the positive. "We think if we get anything out of D.C. in this tight time it is great," said Linda Mullen, spokeswoman for the state Department of Transportation, which ultimately will decide whether to rebuild the viaduct or replace it with a tunnel.

"This is like winning the Tour de France," said Rep. Rick Larsen, D-Lake Stevens, "like winning the yellow jersey."

But at the end of the Tour de France, you know the results. At the end of the congratulatory news conference yesterday, there were reports that some senators who had signed the mammoth transportation bill were having second thoughts about it, unrelated to the viaduct.

"I saw the Democrats' press release on it (viaduct funding) while I was on the House floor," Reichert said. "It was not a done deal yet."

Meanwhile, Larsen said no one on the House-Senate conference committee directly linked repeal of the gas tax to the loss of federal money. But, he added, "No one in Washington state should fool themselves into thinking the federal government will backfill" the money if the tax is repealed.

The gas tax is expected to provide about $2.2 billion for the project.

Finally, the issue of whether the viaduct will be rebuilt or replaced with a tunnel remains controversial.

Murray and the other delegates declined to declare their choice. Instead, they carefully described the decision as a regional matter that will be "confined" by the money available. Replacing the viaduct with a tunnel could cost $4 billion, about $1 billion more than a re-build.

Alicia Mundy: 202-662-7457 or amundy@seattletimes.com