Only three official candidates remain in the 2016 presidential election race.

Only Bernie Sanders stands in the way of a showdown between Hillary Clinton and Donald Trump.

Clinton is taking nothing for granted as California's mega-primary approaches, reaching out to Hispanic and black voters in the hope of waging a final knockout against rival Sanders. Clinton's visit to the Golden State Thursday coincides with Cinco de Mayo, the annual celebration of Mexican culture and heritage. She also plans to rally supporters in the gymnasium of a community college that serves heavily Hispanic cities on the edge of Los Angeles.

Meanwhile, Senate Majority Leader Mitch McConnell says Trump, as the Republican Party's presumptive presidential nominee, has the "opportunity and the obligation" to unite the GOP. In a statement, McConnell says he committed to supporting the nominee chosen by Republican voters and noted that Trump is on the verge of clinching that nomination. But McConnell's statement was hardly a full-throated endorsement.

The Kentucky Republican says his party is committed to "restoring economic and national security" and preventing what he characterized as a "third term of Barack Obama" if Democratic front-runner Clinton wins the White House. He says Trump now must unite the party around "our goals."