Senate Majority Leader Bill Frist (R-Tenn.) is turning his attention toward his party’s conservatives in the latest — and likely last — bid to pass a bicameral budget resolution this year.

In a meeting today with Frist and Senate Budget Chairman Don Nickles (R-Okla.), Sens. Olympia Snowe (R-Maine) and Susan Collins (R-Maine) — two key moderate holdouts on the budget — signaled their willingness to vote for a one-year budget resolution that they had previously rejected as inadequate, as long as the Senate first adopts a rules change that implements strict pay-as-you-go, or “PAYGO,” budget rules for multiple years.

With the votes of Collins and Snowe, Frist could ensure passage of the languishing budget resolution, but only if he can convince conservatives opposed to PAYGO to either vote for it or at least to allow the proposal to come to the floor without procedural roadblocks. PAYGO requires new mandatory spending and tax cuts to be offset. Only by securing 60 Senate votes could the rules be overridden.

“Senator Frist does want to move forward” with the rules change proposal, said Frist spokeswoman Amy Call, who added that Frist would likely not start talks with conservatives until the Senate reconvenes next week.

“Hopefully by next Monday or Tuesday we’ll have a better idea of where things stand,” Call said.

Snowe and Collins, along with Sens. Lincoln Chafee (R-R.I.) and John McCain (R-Ariz.), have withheld their votes from the House-Senate negotiated budget resolution conference report for nearly four weeks because of what they say is a lack of strong spending restraints.

Chafee and McCain, who also participated in the meeting with Frist and Nickles, remained cool to the notion of voting for a one-year budget resolution, with or without the rules change.

Frist’s office actually floated the notion of changing Senate rules to implement PAYGO two weeks ago. At the time, conservatives balked, sources said. But now that Snowe and Collins have essentially made the proposal their final offer, Frist appears to be willing to press the issue with the rest of the Senate GOP caucus.

Still to be decided is how long the PAYGO resolution would last. Collins reportedly suggested a three-year duration, while Snowe appears to prefer the Senate’s original plan to impose PAYGO for five years.

While the three-year proposal is seen as more likely to assuage the concerns of conservatives who don’t want new tax cuts potentially curtailed by the strict spending rules, Democrats, who made up the bulk of the supporters of the original five-year plan, could still balk, noted one Senate GOP aide.

On the other hand, Democrats may be hard-pressed to vote against another five-year proposal, the aide said.

Either way, the Senate’s 49 Democrats remain key to the puzzle. They voted almost unanimously to institute PAYGO during the Senate’s budget debate in March, but also voted in unison — save for Sen. Zell Miller (D-Ga.) — against passage of the budget resolution.

Given that Democrats are still likely to oppose the final budget blueprint, Frist must also convince his conservatives to support final passage in addition to stepping aside for passage of the rules change.