Protests began outside the Thai parliament today as the country's military moved to block the election winner from becoming Prime Minister - because he wants to legalise criticism of the monarchy.

Footage shows the Sappaya-Sapasathan building in Bangkok lined with banners, posters, and signs as demonstrators urged junta-appointed senators to give way to Move Forward Party leader Pita Limjaroenrat as the country's leader on July 13.

Pichet Chuamuangphan, the second deputy House speaker and a Phue Thai Party MP, said a 50-metre section of the Sappaya-Sapasathan had been barricaded to keep protesters out. The rallyists have set up food, drink and clothes stalls as part of the planned demonstration.

Pita Limjaroenrat won the most votes in a national poll in May but the senators have vowed to block him from becoming prime mister over the party's manifesto to remove the controversial lese majeste law, which can see residents jailed for as little as liking or sharing social media posts critical of the institution.

The Harvard University graduate will need to collect at least 376 votes out of 500 MPs and 250 senators to become the next prime minister.

If no decision is reached, parliament will reconvene on July 19 and 20.

The unrest has flared up sending the coutry's currency lower after Move Forward Party won the most seats in a national poll on May 15.

A junta-appointed cabal of 250 'senators' handpicked from the country's benighted institutions will now cast the deciding votes on which party can govern - rendering any elections a sham.

The ultra-conservative senators - branded 'dinosaurs' by critics - have pledged their loyalty to protecting the monarchy and vowed to prevent the Move Forward party from entering government due to its stance on modernising the state and watering down the Lese Majeste law, which they see as a threat to national security.