By Trevor Hunnicutt

(Reuters) - Herman Cain, facing resistance from his own political party as U.S. President Donald Trump's pick to fill a seat on the Federal Reserve Board, withdrew Monday from consideration for the post, citing what he said would be a decrease in influence and pay.

Four Republican U.S. senators have expressed reservations about seating Cain at the Fed, likely enough to deny him the support he needed to secure Senate confirmation for the post.

Economists and critics have also expressed concerns about loyalists of Trump serving on the traditionally nonpartisan central bank.

Cain said he had been planning to defend his nomination.

"But the cost of doing this started weighing on me over the weekend," he said in commentary published on the conservative website Western Journal. "I also started wondering if I’d be giving up too much influence to get a little bit of policy impact."

Cain delivers a stream of conservative commentary daily by Twitter and via a radio show. He also gives frequent speeches. A job at the Fed would bar him from those activities.

"Without getting too specific about how big a pay cut this would be, let’s just say I’m pretty confident that if your boss told you to take a similar pay cut, you’d tell him where to go," said Cain.

Trump announced Cain's withdrawal earlier on Monday.

Cain has been a public advocate of many of Trump's policies, as has Stephen Moore, a fellow at the conservative Heritage Foundation think tank, whom Trump has also said he wants to nominate for one of two vacant seats on the seven-member Fed Board of Governors in Washington.

Several Democrats on Monday renewed calls for Moore to be taken out of consideration.

Cain had said he was under attack as a nominee because he is a conservative. Cain's bid for president in 2012 was derailed by accusations of sexual harassment that recently resurfaced and which he has repeatedly denied.

Cain did not respond to a phone call requesting comment on Monday.

The top Democrat in the U.S. Senate, Chuck Schumer, said Cain's "failure to garner adequate support should not be used as a pathway by Senate Republicans to approve Stephen Moore, who is equally unqualified, and perhaps more political."

Schumer said in a statement that Moore "poses a danger to the economic stability of our country" and called on Republicans who have a majority in the Senate to force him out of consideration.

Moore did not respond to an email seeking comment.

Central bank independence from short-term politics is seen as important to prevent influence that could lead to runaway debt, inflation and financial instability.

Trump elevated Jerome Powell to Fed chairman a year ago but has frequently criticized him for the U.S. central bank's interest rate increases.

Cain, the former head of the Godfather's Pizza restaurant chain, served as chairman of the Kansas City Fed's board in the mid-1990s.

The Fed in March brought a three-year rate-hike cycle to an abrupt end as it abandoned projections for any further rate increases this year.

(Additional reporting by Tim Ahmann and Ann Saphir; Editing by Meredith Mazzilli and Cynthia Osterman)