President Barack Obama speaks at a rally Sunday in North Las Vegas. Obama was in Nevada to boost Hillary Clinton's presidential campaign and help Democrats in their bid to retake control of the Senate.

SAN DIEGO — President Barack Obama is stepping up the pace of his campaign to boost Hillary Clinton as his successor while pushing as well for Democrats to retake the Senate, visiting tightly contested Nevada before headlining party fundraisers Monday in California.

Getting into the Las Vegas spirit Sunday night, Obama told Nevadans they have a winning hand in Clinton and Senate candidate Catherine Cortez Masto.

“You’ve got black jack,” Obama told a crowd of 3,000 boisterous supporters packed into a local high school, while another 2,100 were outside.

Obama was unsparing in his criticism of Republican presidential nominee Donald Trump, describing the billionaire businessman as unfit to serve as president. Obama said that for years, Republican politicians and far right media outlets have served up “all kinds of crazy stuff” about him, Clinton and Sen. Harry Reid, the Nevadan who leads Senate Democrats. Obama cited as an example those who questioned whether he was born in the U.S. and others who argued that he aimed to take away everybody’s guns.

“Is it any wonder that they ended up nominating somebody like Donald Trump,” Obama said, claiming that Republican lawmakers stood by and said nothing because it gave them a political advantage.

“So Donald Trump did not start this,” Obama said. “He just did what he always did, which is slap his name on it, take credit for it and promote it.”

Democrats need to pick up five seats to gain the majority in the Senate, or four if they hang onto control of the White House. The vice president casts tie-breaking votes in the Senate.

Polls indicate that the presidential and Senate races in Nevada are extremely tight. Reid’s seat is considered the only one Republicans could reasonably flip to their side this election. Outside groups have spent tens of millions of dollars trying to influence the outcome.

Obama’s standing in the polls has made him a popular surrogate for congressional candidates hoping that a decisive Clinton victory will benefit them as well. The White House has said that Obama’s primary mission in the next two weeks will be helping Clinton, but he will also use his appearances to support Democratic candidates up and down the ballot, even in some state legislative races.

Obama will participate in another fundraiser for Clinton today in San Diego. He will then fly to Los Angeles for a fundraiser and to participate in a taping of Jimmy Kimmel Live!