By Peter Gosnell

(Reuters) - Australian mining magnate and politician Clive Palmer confirmed on Saturday his Palmer United Party (PUP) would seek to win Senate seats in every Australian state in the July 2 election, despite a slump in support.

Palmer briefly became a political powerbroker after riding a wave of dissatisfaction with the major parties in the 2013 election to claim three upper house Senate seats and win a seat for himself in the lower house of Parliament.

However, two Senators left the party, Palmer has been caught up in legal battles over the closure of a nickel smelter he owns with the loss of hundreds of jobs, and support for his party has sunk to just 1 percent nationally, according to a recent poll.

Speaking in Brisbane ahead of what is expected to be a close election between the ruling Liberal/National coalition and the Australian Labor Party, Palmer told supporters his party was a bulwark, protecting them from the excesses of the major parties.

"The Liberal and Labor parties and our centralized media have sought to destroy our party," he said.

The two main parties are running neck and neck in polling.

Voters will also choose all members of the upper house for the first time since 1987 after the government dissolved both houses of parliament after the Senate repeatedly blocked legislation.

Polling shows more than a quarter of voters could support independent or minority parties like Palmer's, however recent voting reforms will make it harder for smaller parties to enter parliament through vote sharing deals.

Palmer has decided not to recontest his seat, while his party - which stood 150 aspirants across every lower house seat in the 2013 election - will only contest the upper house Senate.

(Reporting by Peter Gosnell; Editing by Richard Pullin)