Democrats badly want to get back control of the Republican-controlled Senate in the Nov. 8 election, and are sending Obama, Michelle Obama and Joe Biden to states where close races could tip the balance.
In Nevada, Obama reserved most of his firepower for mocking three-term Republican US Representative Joe Heck, who had supported his party's presidential candidate until earlier this month when Donald Trump's campaign went into crisis mode by the release of a video in which he lewdly bragged about groping and kissing women.