Spain's opposition Socialist party leader Pedro Sanchez is vowing that his group will vote against conservative acting Prime Minister Mariano Rajoy's candidacy to form a government — a move that could torpedo chances of breaking Spain's political deadlock anytime soon.

In a first investiture vote Wednesday, Rajoy needs an absolute majority in the 350-seat Parliament. He currently stands six votes short, having only his party's 137 lawmakers and the backing of 33 others.

If Rajoy loses Wednesday, he has a second chance Friday when he only needs more votes in favor than against. Still all signs indicate he won't pass that test either.

If no government is in place in two months' time, Spain may have to hold its third election in a year.