As Donald Trump insists that the election is rigged against him, one of his top surrogates, former Mayor Rudy Giuliani, is giving him some backup by pointing to his personal loss at the polls. Giuliani is suggesting he lost the 1989 mayor's race because of voter fraud. Our Grace Rauh has been digging into his claim and finds no hard evidence to suggest it is true. Here is her report.

Before Rudy Giuliani finally won City Hall he narrowly lost to David Dinkins in 1989 by less than 50,000 votes.

That election was nearly 30 years ago, but it's coming up again as Donald Trump argues the presidential election is rigged.

"When I ran for mayor of New York City the first time some people voted eight or ten times," Giuliani said Sunday.

Giuliani has made this claim before, but there does not appear to be any concrete evidence to back him up.

"I don't know why he is raising it now," said democratic consultant George Arzt. "But it's revisionist history."

NY1 spoke with former aides to Giuliani and a top Republican official. They suggested three reporters witnessed illegal voting. Two told us that was not the case. A third, Fred Dicker, said he saw dozens of mentally disabled people bused in to vote in 1993, presumably for Dinkins, but in 1993 only.

The former executive director of the state Republican Party says an election official admitted to him that massive fraud occurred the year Giuliani lost. Former Congressman John Sweeney says Dan DeFrancesco, then the executive director of the city's Board of Elections, told him this about the '89 race:

"We stole, we took 150,000," Sweeney says. "I interpreted that as saying they were able to steal 150,000 votes. It was stunning."

DeFrancesco is deceased. So why didn't Sweeney and others challenge the results of the mayor's race with that alleged admission?

"We really weren't looking back we were looking forward," Sweeney said.

The city's Department of Investigations reportedly examined allegations of voter fraud in 1989 but there are no news reports to indicate they found anything.

Instead, Giuliani's campaign created a beefed-up poll watching operation for Election Day in 1993. And Giuliani won that year — by about 50,000 votes.