Former Vice President Joe Biden excoriated Donald Trump at an early vote rally in Las Vegas, Nevada, on Saturday, telling a crowd of Democrats and union workers that American values had been "shredded" by Trump - a man "who's all about himself".
Biden, whose appearance ended shortly before Trump's began, said the United States was founded "on an idea, the American idea, basic fundamental decency, and it's being shredded".
President Donald Trump is touting high job numbers as the reason his Republican Party should win the midterms as a new poll shows him with a record high approval rating - and Democrats winning in November.
Trump said that Biden only had 193 people at his campaign rally in Las Vegas. He has sought to focus on immigration as one of the defining election issues and has falsely accused Democrats of wanting "open borders" and encouraging illegal immigration.
Voter enthusiasm is up 15% and 7% from the 2014 and 2010 midterms, respectively, indicating that this year's elections could show larger than average voter turnout.
President George W. Bush had a much higher approval rating - a post-9/11 67 percent - and gained eight seats for the Republican Party in the House. "It's bigger than politics", Biden said.
In a tweet, the president said Heller had "become a good friend" who was "all about #MAGA".
Rep. Jacky Rosen, the Democratic Senate candidate in Nevada, voted in favor of extending the individual tax cuts permanently even though she opposed the initial tax bill.
"It is deeply sad but unsurprising that we now see that ugliness rearing its head", she said.
But Heller once had rocky relations with Trump and had returned a campaign donation from then-candidate Trump over Trump's immigration rhetoric. Obama came along and took him off the trash heap and made him vice president.
During his gaggle with reporters on Saturday, Trump also addressed the controversy surrounding the disappearance and death of Saudi journalist Jamal Khashoggi, who entered - but never reemerged - from the Saudi Arabian consulate in Istanbul, Turkey.
The country's immigration system has long vexed politicians from both parties, and Republicans themselves have torpedoed near-compromises in recent years.
But the poll found that Democrats led among all women at 57 percent to 32 percent, among Latinos at 66 percent to 26 percent, and those ages 18 to 34 at 58 percent to 32 percent, the poll found. Chuck Schumer of NY and Rep. Nancy Pelosi of California.
Heller and Rosen held their first and only debate of the campaign on Friday.
It was not precisely clear what Trump was referring to, and the White House did not immediately respond to a request for clarification.
Rallying thousands of supporters in an Arizona aircraft hangar for GOP Senate candidate Rep. Martha McSally, Trump warned of dire consequences if her opponent, Democratic Rep. Kyrsten Sinema, is victorious.