BANGKOK: Thailand's Pheu Thai party on Thursday received a boost in its efforts to form a government after a ninth party joined its alliance and a senior member of a rival, military-backed party pledged its support to try to end months of deadlock.

Thailand has gone nearly five months under a caretaker government after the election-winning Move Forward party leader's bid for premier was blocked twice by conservative and pro-army opponents.

Move Forward's former ally, the second-place Pheu Thai party, last week took the lead in trying to form a government and is expected to face the same opposition.

Pheu Thai is set to nominate real estate tycoon Srettha Thavisin for premier and needs the support of more than half the bicameral legislature including the royalist-dominated upper house.

Previous Pheu Thai governments, backed by the billionaire Shinawatra family, were ousted by military coups in 2006 and 2014, when its interests clashed with the country's powerful old money elites and royalist military.

But on Thursday, a lawmaker from a rival party said they would support Pheu Thai in overcoming the deadlock.

"We are ready to support Pheu Thai because the country needs a government to move on," lawmaker Pai Leeke from the pro-military Palang Pracharat party told reporters, adding that 40 of its elected parliamentarians had agreed on the matter.

Palang Pracharat's leader, Prawit Wongsuwan, was a member of the military that removed Pheu Thai in 2014. The party did not immediately respond to a request for comment.

"We have not been approached by Pheu Thai. Whether or not we join the government is a small matter - we have to move past this, then we can have talks," Pai said.

Pheu Thai so far has formed an alliance with nine parties, with 238 seats in the lower house. Its prime ministerial candidate Srettha would still need support from the upper house, which was appointed by the junta and has sided with conservative forces.