By Gram Slattery

WILDWOOD, New Jersey (Reuters) - Republican presidential candidate Donald Trump attacked the Manhattan judge and prosecutor in his New York criminal trial, while hinting at a range of possible economic policies at a sizable rally in New Jersey on Saturday.

Speaking before tens of thousands of supporters on a chilly beach on the Atlantic coastline, the former president disparaged District Attorney Alvin Bragg's appearance and dismissed the various state and federal charges he faces as a form of political persecution.

"Fat Alvin, corrupt guy," said Trump, who is on trial for allegedly falsifying business records to hide a hush money payment to a porn star before the 2016 presidential election that he won.

Trump also took aim at the trial judge, Justice Juan Merchan, accusing both men of working at the behest of President Joe Biden, his Democratic rival in this year's presidential rematch - an allegation for which there is no evidence.

"They're doing the bidding for crooked Joe Biden. This is all being done by crooked Joe Biden."

The New York case is one of four state and federal criminal trials Trump faces and may be the only one to be held before the Nov. 5 election. He has pleaded not guilty in all of them, portraying them as politically motivated.

Trump was in the beachside town of Wildwood, New Jersey, a conservative part of an otherwise Democratic state.

Though the former president told supporters he plans to win New Jersey, that is unlikely given that Biden beat the then-president in the state by 16 percentage points in 2020.

But Wildwood is less than 90 minutes from Pennsylvania, one of the nation's most competitive states, and it is a popular weekend spot for residents of metropolitan Philadelphia. Trump referred frequently to Pennsylvania during the rally.

He alluded to policies including a tax cut and fresh tariffs should he return to office.

Recounting a conversation with an unnamed automotive executive who had built factories in Mexico, Trump said he had pledged a 200% tariff on some imported cars. It was not clear what countries would be affected by the tariff or if his recounting of the conversation amounted to a formal policy proposal.

The Biden White House is itself poised to dramatically raise tariffs on Chinese electric vehicles in the coming days.

"I said, 'I will put a 200% tax on every car that comes in,'" Trump told the crowd.

Trump also said he would halt offshore wind projects in New Jersey and pledged to implement a new tax cut, without offering details.

Trump has come out in favor of extending a major tax cut that he signed to law in 2017, and Reuters reported in April that Trump was mulling an additional tax cut geared toward the middle class.

"Instead of a Biden tax hike, I'll give you a Trump middle-class, upper-class, lower-class, business-class big tax cut," he said.

Warming up the crowd was North Dakota Governor Doug Burgum, a one-time rival in the Republican primary race. The governor has since become a top contender to be Trump's vice-presidential candidate, according to multiple people who have talked to the former president. Trump appeared to allude to Burgum taking a major administration role in his speech.

"Get ready for something, OK?" Trump said, while discussing Burgum. "Just get ready."