RICHMOND, Feb. 23 -- Republican delegates and senators who have been negotiating a deal on transportation funding unveiled a new plan Friday that could raise more than $1.5 billion for roads and mass transit every year, setting up a final showdown vote Saturday in the General Assembly.

Most of the new money would come from borrowing and would be paid back using cash from the general fund -- which has been a sore point in negotiations for weeks.

Republicans who crafted the massive, 106-page bill during intense and secret talks over the past week described it as the "last, best hope" for road improvements from the fractured legislature, which is scheduled to adjourn for the year after voting on the bill.

Gov. Timothy M. Kaine (D) immediately condemned the plan as a threat to core state services, which get their money through the general fund. He raised the specter of an extended session, vowing to "make sure the legislature does not get out of here without a commitment to fixing the transportation challenges that face Virginia."

Kaine's staff has drafted a special session order that would call the legislature back into session at noon Monday if the plan is defeated Saturday, said two sources familiar with the order. House Republicans, meanwhile, voted privately Friday night to refuse the order if it comes, three sources in the caucus said.

The plan does not include any new tax increases on gas, sales or income, provisions that Democrats and some moderate Republicans in the Senate have said are necessary to adequately fund the state's transportation needs and to protect schools, public safety and other services. Kaine's Democratic allies in the Senate promised to defeat the bill.

The House of Delegates and the Senate, which are both controlled by the GOP, are scheduled to take separate votes on the plan Saturday. Lawmakers from both parties said the plan is likely to pass easily in the House. But they said the vote could be very close in the Senate, where proponents said the margin of victory could be a single vote.

If the measure fails, the result could be another bitter stalemate for Virginia lawmakers, who repeatedly failed to reach an agreement on transportation in last year's General Assembly and in a subsequent special session on road funding. In November, all 140 lawmakers will face voters, who have said repeatedly in polls and interviews that they are angry about the legislative standoff on such an important quality of life issue.

"A state that lacks the political will to fund its transportation responsibilities is neither well managed or a good place to do business," said Bob Chase, president of the Northern Virginia Transportation Alliance. "This package puts a lot of money on the table. It's too much money to walk away from."

Friday's proposal closely resembles a compromise negotiated by a handful of GOP lawmakers at the beginning of the session. That early draft was passed by the House but was changed dramatically in the Senate, where a new sales tax on gasoline was added to replace general fund money. The conference committee of delegates and senators revived the House plan with some modest changes.

The new compromise proposal would build roads and fund improvements in transit using $2.5 billion in bonds that would be financed from the state's general fund. Northern Virginia stands to gain an additional $400 million a year, according to the proposal, which would be raised from local taxes and fees approved by local officials.

"If this plan is enacted, you get $400 million a year, year after year after year for Northern Virginia. You get $2.5 billion in bonds, statewide. You get much needed reform in VDOT," said House Speaker William J. Howell (R-Stafford). "This goes a long way toward addressing the transportation problems we have in the commonwealth."

Del. David B. Albo (R-Fairfax) said the plan would be a boon to Northern Virginia commuters, who struggle daily with some of the nation's worst traffic congestion. He said expressions of caution by elected officials in Fairfax and Prince William counties are unfounded.

"I would literally be shocked if Fairfax County would bypass $200 million in road money going just to the county year after year after year," Albo said.

But Kaine, who won in 2005 in part by vowing to fix the state's traffic problems, said he refuses to be bullied into accepting a roads plan that he called "bogus," "irresponsible" and "a very bad idea."

He told reporters that the plan contains provisions that strip power from the governor's office and take too much money from other state services. He also said the plan fails to pump enough money into rural areas outside the state's suburban communities.

"Taking money out of the school budget to pay for road bonds is a very bad idea," Kaine said. "To me, it has all the earmarks of an effort not to solve a transportation problem."

If the bill passes, Kaine said, he promises to use his power to amend bills to "do significant surgery" on it. If it fails, Kaine could demand a special session, perhaps immediately, to start working on a new approach. The governor said his staff has already prepared another transportation plan, but he refused to provide details.

Howell and his colleagues said the governor and his allies are turning their backs on billions of dollars for road construction and maintenance.

They said the latest proposal reduces to $175 million a year the amount of money diverted from the general fund, which pays for colleges, health care, public safety and schools. Previous proposals had shifted $250 million.

The plan also has provisions aimed at giving local governments more control over their own roads. And it gives lawmakers more control over transportation by letting them appoint members of the Commonwealth Transportation Board, which directs transportation projects.

It does not contain general tax increases championed by some in the Senate. And it does not include a statewide increase in the sales tax on cars, which Kaine proposed six days after taking office in 2006.

House Majority Leader H. Morgan Griffith (R-Salem) called those ideas "just old oatmeal that's been reheated. I'm telling you, that stuff's nasty."

Saturday's vote will be the culmination of an intense week during which a handful of House and Senate negotiators tried to design a transportation bill that would be accepted by conservative delegates but also by the more moderate senators.

To pass, the bill must receive 21 votes in the 40-member Senate and 51 votes in the 100-member House of Delegates. Lawmakers in both parties said it remains unclear whether the Republican plan has enough support to pass in the Senate, where opposition among Democrats and the chamber's leading Republican, John H. Chichester (Northumberland) is fierce.

Throughout the week, the plan morphed repeatedly as lawmakers huddled in corners, chatted on cellphones and retreated to closed-door meetings in the General Assembly building next to the Capitol. The lawmakers met until midnight Thursday putting the final touches on the plan.

Among those touches, GOP sources said, is a $22 million earmark for transit funding in Loudoun County, aimed at getting freshman Sen. Mark R. Herring (D-Loudoun) to vote for the package. Herring declined to comment, and others in his party predicted that the logrolling effort by Republicans would fail.

Northern Virginia Democrats in the House expressed skepticism about the proposal but said the pressure to approve it is great.

Asked whether no deal was better than the deal offered Friday, House Democratic Caucus Chairman Brian J. Moran (D-Alexandria) said: "We're in a tough spot. The Northern Virginia plan is a substantial plan. But you have to look at the total package. So it's really tough."

Staff writer Amy Gardner contributed to this report.