Following Tuesday night's Indiana primary, it now looks all but certain that Donald Trump will reach the 1,237 delegates needed to officially clinch the Republican Party's presidential nomination. Trump's last remaining rivals, Texas senator Ted Cruz and Ohio governor John Kasich, have now both suspended their campaigns, indicating that they do not see a viable path to defeating Trump.

Months ago, at the start of the primary season, there were as many as 17 major candidates running for the GOP nomination. One by one, they dropped out, including early favorites Jeb Bush, Scott Walker and Marco Rubio. Cruz and Kasich had been holding on in hopes of finding a way to grab the nomination away from the clear leader, Trump, at the July party convention in Cleveland. Those hopes are now gone, barring some unforeseen major event.

News organizations are generally stopping short of calling Trump the "presumptive" nominee, at least until he crosses the 1,237-delegate threshold. However, the chairman of the Republican National Committee, Reince Preibus, did not:

The immediate future looks quite clear. Trump will almost certainly be at the top of the ticket of the Republican Party in the 2016 presidential election, a development very few would have predicted a year ago.

The billionaire businessman stormed into the process announcing plans to build a wall on the southern border of the U.S. and insisting Mexico would pay for it. Trump repeatedly disparaged his opponents, often in crude and personal ways that veteran political operatives and pundits claimed would doom him. But all along he only grew more popular with the GOP base, gradually adding state victories, accumulating delegates and watching his percentage of the vote rise and rise.

His final two rivals now out of the way, Trump stands alone at the top of the Republican Party, with about six month to go till Election Day.