WASHINGTON, Sept. 5 — With a mixed picture emerging about progress in Iraq, Senate Democratic leaders are showing a new openness to compromise as they try to attract Republican support for forcing at least modest troop withdrawals in the coming months.

After short-circuiting consideration of votes on some bipartisan proposals on Iraq before the August break, senior Democrats now say they are willing to rethink their push to establish a withdrawal deadline of next spring if doing so will attract the 60 Senate votes needed to prevail.

Senator Carl Levin, Democrat of Michigan, said, “If we have to make the spring part a goal, rather than something that is binding, and if that is able to produce some additional votes to get us over the filibuster, my own inclination would be to consider that.”

Democrats would need to lure the 60 senators in order to cut off a likely Republican filibuster.

The emerging proposal by Mr. Levin and Senator Jack Reed, Democrat of Rhode Island, would still order the administration to begin pulling at least some combat troops out of Iraq, probably by the end of the year. It is not clear what other provisions the measure may include.