Senate Democrats put their congressional campaign spending limits proposal on the shelf Friday after losing another attempt to overcome Republican opposition and force a vote on the issue.

Fifty-three senators, including four Republicans, voted to invoke cloture, or end debate, but this was seven votes short of what is needed to suspend the Senate's unlimited debate rule.This was the 10th time since last June that Majority Leader Robert Byrd, D-W.Va., lost a cloture on the divisive issue.

The first eight attempts came over a bill that would have established a voluntary system of limits for Senate campaigns.

The latest losses on Thursday and Friday prevented a vote on a proposal by Sen. Ernest Hollings, D-S.C., to amend the Constitution to overcome a Supreme Court ruling that mandatory limits violate free speech rights.

Byrd said after Friday's attempt that six of the 10 absent senators would have voted for cloture, leaving him "within striking distance" of the needed 60 votes.

He said that while he was pulling the issue from the floor, members shouldn't assume that he would not bring it back in the future.

Senate Minority Leader Bob Dole, R-Kan., said Republicans don't oppose placing limits on campaign spending but as a group don't want to tamper with the Constitution or vote for any legislation that would favor Democrats.

"I'm willing to try to work out some bipartisan measure that is fair across-the-board and doesn't discriminate against anybody," Dole said. "We are spending too much money."

He and Sen. Mitch McConnell, R-Ky., said that even if Byrd succeeded in winning cloture for the proposed constitutional amendment, it was unlikely the measure could get the 67 votes needed to pass the Senate.