By Radu-Sorin Marinas
BUCHAREST (Reuters) - Romania's ruling Social Democrat party (PSD) will seal a new partnership with a junior ally on Thursday, looking to secure its grip on power before a national election in 2016, party sources told Reuters.
Prime Minister Victor Ponta's government has looked vulnerable to defections ever since his surprise defeat in a presidential election in November. Two smaller political parties have already pulled support from his coalition in the aftermath.
A new deal with the National Union for the Progress of Romania (UNPR) will provide crucial support for Ponta's cabinet, giving it a functioning majority and thwarting potential attempts by the opposition to topple the cabinet in a censure motion. With 52 MPs, the UNPR is Romania's third-largest party.
The partnership could help stave off trouble for Ponta as he looks to push legislation for sweeping tax cuts through parliament and navigate potentially difficult negotiations with the International Monetary Fund over a standby aid agreement.
"Our party is likely to overwhelmingly endorse a protocol to run on joint electoral lists with UNPR in both municipal and parliament elections," a member of the PSD's executive committee, which meets on May 7 to discuss the plan, said.
"It's going to be politically beneficial for both sides," a second senior PSD member told Reuters.
A UNPR senator said he expected a plan to run on joint electoral lists with the PSD in next year's elections "will be endorsed by our PSD colleagues tomorrow".
"We aim to keep our representation of 50 seats in parliament, but more details are to be further discussed," the official said. He said about 10 percent of eligible posts, including county councillors in local elections, would be awarded to his grouping.
The UNPR is a leftist party which supports scrapping Romania's 16 percent flat income tax rate in favour of a progressive system, and holds the interior ministry portfolio in Ponta's cabinet.
The party has trebled its number of seats in parliament since a 2012 general election with defectors from other parties.
(Editing by Matthias Williams and Louise Ireland)