PARIS, June 18 (Reuters) - Far-right party leader Jordan Bardella called on French voters on Tuesday to give his party an absolute majority in upcoming parliamentary elections so that it is able to govern effectively.

Bardella, whose National Rally (RN) party has its first real chance of winning national power in the June 30 and July 7 ballot, watered down some of his party's pledges, saying they would not immediately cut VAT on a list of 100 essential goods.

Opinion polls have consistently placed the eurosceptic, anti-immigration RN first since President Emmanuel Macron's shock decision earlier this month to dissolve parliament.

But those pollsters who have attempted the tricky exercise of projecting a second-round forecast for France's 577 constituencies see the RN failing to secure the absolute majority that guarantees power and the ability to pass laws without allies.

"I'm not going to sell to the French reforms that I cannot carry out. I'm telling them that in order to act, I need an absolute majority," Bardella told CNews TV.

He had the same message for Le Parisien newspaper.

"To govern, I need an absolute majority. Who can believe that we would be able to change the daily lives of the French by cohabitation with a relative majority? No one. I say to the French: to try us, we need an absolute majority."

Bardella, 28, also confirmed plans to quickly slash VAT on energy from 20% to 5.5%, which he wants to be his first move as prime minister, the paper said.

For this reason too, he urged more voters to rally behind him and Marine Le Pen, the RN's former leader and the party's candidate in France's next presidential election due in 2027.

"If I run the country without an absolute majority, I won't be able to cut VAT on fuel and on gas ... I won't be able to drastically cut immigration," he told Le Parisien. (Reporting by Dominique Vidalon and Ingrid Melander Editing by Gareth Jones)