A small group of Republicans facing election fights next year have rallied around war legislation they think could unite the GOP: call for an end to U.S. combat in Iraq, but wait until President Bush is out of office.

The legislation was deemed essentially a nonstarter by Democrats Friday and underscored the difficulty Congress has in striking a bipartisan compromise on the war. What attracts Democrats has repelled Republicans and vice versa, making it impossible so far to find a middle ground.

"To try to put this off until after the election, rather than a reasonable period of completion, I believe would be to unnecessarily introduce a political element to what is a bipartisan effort," said Sen. Carl Levin, the Democratic chairman of the Armed Services Committee.

The proposal, by Sen. George Voinovich, R-Ohio, would require that Bush change the mission of U.S. troops from combat to primarily support roles, such as training Iraqi security forces and protecting U.S. infrastructure in Iraq. His legislation would set a goal of completing such a mission transition within 15 months.

If enacted immediately, that timeline would not kick in until Bush's last couple weeks in office.

Co-sponsors of the bill include Sen. Lamar Alexander of Tennessee, Elizabeth Dole of North Carolina and Norm Coleman of Minnesota. Of the sponsors, only Voinovich is not up for re-election in 2008.

Voinovich, Alexander and Coleman in particular have been critics of Bush's war strategy, citing voter frustration with what seems to be an open-ended military commitment in Iraq. Coleman has become a popular political target by anti-war groups hoping to replace him with a Democratic candidate willing to demand troop withdrawals.

For months, these senators and other GOP members were seen as potential supporters of Democratic proposals to challenge Bush on the war. But the group has refused any legislation that includes a timetable for troop withdrawals, contending they do not want to tie the hands of military generals and a wartime president.

However, Democrats say they aren't in a position to forego deadlines. Under substantial pressure from voters to consider nothing less, party leaders have repeatedly called for votes on legislation ordering troops home. But each time, the bill sinks in the Senate where Democrats lack the 60 votes needed to surmount a key parliamentary obstacle to passage.

Levin, D-Mich., has been leading the anti-war effort for the Democrats. He said he worked closely with Voinovich in recent days in the hopes of striking a compromise proposal that could muster the necessary 60 votes.

But neither side was able to get past one big sticking point: when Bush should be pressured to end combat and hand the mission off to the Iraqis. Voinovich thought by extending the date to 15 months from now, it would take the 2008 elections off the table and entice Republicans to support it.

But that 15-month timetable "made it just unacceptable to most Democrats," Levin said.