Clinton v Trump is on - but race row is hindering 'The Donald'
So now we know. Both Donald Trump and Hillary Clinton have passed the delegate threshold they need to become their party's respective candidates, setting the stage for November's election.
Although a handful of states still have to vote, the two candidates hold apparently insurmountable leads. Technically, however, their races are not over until next month's party conventions - and both face challenges from within.
So where does the US election stand at the moment, and where do we go from here?
The Democratic race is, for all intents and purposes, and despite the token protestations of the Sanders campaign, a done deal. Even if Mr Sanders wins the remaining contests by enormous, unrealistic margins he cannot beat Ms Clinton.
He so far has refused to give way, arguing that he has the momentum, and will appeal at the convention to super-delegates - who can vote for whomever they choose - to switch sides.
At one time it looked as if Mr Trump would face significantly more of a challenge from within his party, as conservatives tried to pad the convention with anti-Trump delegates and force through a 'white knight' candidate.
However, since Ted Cruz and John Kasich dropped out of the race in May, the billionaire property mogul has begun the process of winning over the party.
But yesterday, Mr Trump was making the headlines again for all the wrong reasons. Paul Ryan, the Speaker of the House, issued a stinging rebuke of his statements about a judge of Mexican descent, calling them "the textbook definition of a racist comment".
Mr Trump faces a growing backlash from senior Republicans after continuing to claim that the judge in a fraud case over his Trump University program was biased because of his race.
"He's a Mexican," Mr Trump said, explaining his accusations of bias against Judge Gonzalo Curiel, who was born in the US to Mexican immigrants.
"We're building a wall between here and Mexico."
He later said a Muslim judge might also be unable to rule fairly in the case because of his plan to ban Muslims from entering the US. Mr Ryan, the most senior Republican elected official, called those comments "unacceptable".
"I absolutely disavow those comments. I think they're wrong. I don't think they're right-headed and the thinking behind it is something I don't even personally relate to," he said at a press conference in Washington.
Mr Ryan appeared to end a standoff with Mr Trump last week by belatedly offering the presumptive nominee his endorsement, and said yesterday that he would not rescind that support.
But that did not stop him from issuing one of the sharpest critiques in memory by a top party official on that party's presidential nominee.
A day earlier, Lindsey Graham, a prominent Republican senator and long-time Trump antagonist, had said Mr Trump's comments were "the most un-American thing from a politician since Joe McCarthy", which was a reference to the senator who fuelled fears of Communist subversion in the 1950s.
Ted Cruz also joined Marco Rubio and John Kasich in rejecting the comments, meaning all three of Mr Trump's top rivals for the nomination have distanced themselves from him.
The comments underline Mr Trump's difficulties with Hispanic voters in particular, and Democrats are making every effort to tie Republican officials in heavily Hispanic districts, including Senator John McCain, to the party's 2016 standard-bearer.