Spain's acting prime minister is opening a two-day parliamentary debate in hopes of forming a new government and ending an eight-month impasse, but expectations of a breakthrough are running low.

Mariano Rajoy is expected to argue Tuesday that Spain desperately needs a government, not a third election, following two inconclusive elections since December.

To win a new leadership term, Rajoy needs an absolute majority of support from lawmakers in the 350-seat chamber in Wednesday's planned vote. He currently has 170 deputies backing him, six votes short.

Should he fail to garner the needed votes, Rajoy still could prevail in a second vote Friday — if the opposition Socialists abstain from the vote rather than reject him outright. Socialists remain publicly committed to blocking his return to power.