They can't because of jumping Jim Jeffords(Dashcle controls the bills in the Senate now). The Republican Congress three times sent to Clinton a partial birth abortion ban and three times he vetoed it.
That is precisely why pro-lifers tend to be so cynical about it. Republicans in Congress were all in favor of a late-term abortion ban when they knew Clinton would veto it, but their "courage" disappeared once the party was in a position to ensure that anything they passed would be signed into law.