WASHINGTON — A Senate stalemate over legislation to combat human trafficking deepened Thursday, almost certainly delaying a confirmation vote on the president’s attorney general nominee, Loretta Lynch, until mid-April.

Senate Majority Leader Mitch McConnell had planned a vote on Lynch’s long-delayed nomination this week, but put it off when bipartisan support for the trafficking bill collapsed in a partisan spat over abortion funding. McConnell said he wanted to finish the trafficking bill first.

That goal looked farther off than ever Thursday, as competing proposals were advanced to break the impasse, and both quickly rejected by partisans on either side. Sen. Susan Collins, R-Maine, co-sponsored one of those proposals.