BANGKOK, June 4 (Xinhua) -- Thailand's Democrat Party on Tuesday decided to join the coalition led by the pro-government Palang Pracharath Party and vote for Prayut Chan-o-cha as prime minister.

Democrat party leader Jurin Laksanawisit read out a statement after his party conducted a secret voting on whether to join the coalition and support Prayut for post-election prime minister.

A joint House of Representatives and Senate meeting is scheduled on Wednesday during which 500 MPs and 250 senators will elect the new prime minister.

The Democrat party leader confirmed that the three points of demand which his party had raised in exchange for its joining the pro-Prayut coalition have been met.

The demands included the Democrat Party's hand-to-mouth economic measures which will be included in the new government's anti-poverty policy, constitution amendment and transparency in government, Jurin announced.

Jurin said the Democrat Party, the country's oldest party which has turned itself from a large-size party to a medium-size one following the March 24 election, is certainly making a majority government as its 53 MPs are joining in alongside those of a few other parties.

He apparently referred to the Bhumjaithai Party and Chartthaipattana Party which were earlier invited by the Palang Pracharath Party to take part in its coalition.

Democrat MPs and executive board members conducted a secret voting on Tuesday on whether or not to join the Palang Pracharath-led coalition and to pick Prayut for prime minister.

Sixty-one voted in support of joining the coalition and vote for Prayut as prime minister, while 16 voted against it.