Former Republican presidential candidate Herman Cain previously served as a board member at the Kansas City Federal Reserve Bank and is the former chief executive of Godfather's Pizza

Washington (AFP) - Four Senate Republicans were on record Thursday as opposing Donald Trump’s planned choice of former pizza executive Herman Cain to join the US Federal Reserve, essentially scuppering his confirmation before the president officially nominates him.

Trump has had tense relations with the nation’s central bank for months, as he urges a lowering of interest rates and taps unconventional loyalists like Cain to fill empty seats on the Fed Reserve board.

The pressure has led Democrats to raise concerns that the Fed is being politicized.

A handful of Republicans have so far joined Democrats in opposing the controversial Cain.

Senator Kevin Cramer became the fourth Republican in the chamber to come out against him, saying “if I had to vote today, I would vote no.”

Trump’s party holds a 53-47 majority in the Senate, and can afford only three defections if all Democrats vote in opposition to a nominee.

Senate Republicans Lisa Murkowski, Cory Gardner and Mitt Romney have said they will not support Cain.

The 73-year-old previously served as a board member at the Kansas City Federal Reserve Bank and is the former chief executive of Godfather’s Pizza.

He was also a candidate for the Republican Party’s presidential nomination in 2012, but suspended his campaign following allegations of sexual misconduct, which he denied.

“I don’t think Herman Cain would be confirmed by the Senate, and I think the president would be wise to nominate someone who is less partisan and more experienced in the world of economics,” Romney said Wednesday.

Cain is one of two loyalists that Trump has said he would like to place on the Fed board.

The other is Stephen Moore, 59, a controversial economist and former Trump campaign adviser.

Amid rising concern among Democrats about the bank’s politicization, Federal Reserve Chairman Jerome Powell has been invited to meet with congressional Democrats behind closed doors Thursday evening at their annual policy retreat in Virginia, US media reported.

“I personally am very concerned about the independence of the Federal Reserve generally and the independence of its members specifically,” number two House Democrat Steny Hoyer told CNBC.