The votes are already whipped. This seems to be a strategy to delay.

With the Senate working through an all-night session on a package of changes to the Democrats’ sweeping health care legislation, Republicans early Thursday morning identified parliamentary problems with at least two provisions that will require the measure to be sent back to the House for yet another vote, once the Senate adopts it.

via G.O.P. Forces New House Vote on Package of Health Bill Changes – NYTimes.com.