Jeb Bush has finally admitted what's been obvious for months: Republican voters don't want him to be their presidential nominee.

So after an embarrassing finish behind the top three candidates in the South Carolina primary, Bush announced that he was withdrawing from the race.

"The people of Iowa, New Hampshire, and South Carolina have spoken," a choked-up Bush said. "And I really respect their decision. So tonight, I am suspending my campaign."

Bush's withdrawal helps clear up what some pundits have referred to as the "establishment lane" of the GOP primary race, in a way that seems likely to benefit his fellow Floridian, Marco Rubio.

With Bush's exit, he and his well-funded Super PAC will no longer be spending tens of millions of dollars on ads trashing Rubio. And his connected endorsees and fundraisers are also now up for grabs.

When it comes to actual voters, though, Bush's withdrawal may make only a small difference. His support was so negligible that he was only in the low single digits in national polls. And before tonight's embarrassing defeat, he finished in sixth place in Iowa and in fourth in New Hampshire. So it's clear his exit has been in the cards for quite some time.

Bush was thought to be the party favorite. But the party has changed.

When Jeb Bush made clear that he would likely run back in December 2014, it quickly became apparent that he was the favorite of much of the moneyed, lobbyist-connected GOP donor class. This led many to deem him the Republican frontrunner. And, indeed, he did spend most of the first half of 2015 in first place in the polls — though his peak in the HuffPost Pollster average was a mere 15 percent.

A funny thing happened along the way, though — actual Republican elected officials never rallied to Bush's side.

According to FiveThirtyEight's endorsement tracker, Bush was never endorsed by a single sitting Republican governor. And only five senators and a handful of Congress members (many of whom were from Florida) publicly backed him.

The hesitancy of GOP elites to rally to Bush's side shows how much the Republican Party has changed since his brother's presidency. Jeb has been out of politics since early 2007. So, effectively, he missed the economic crisis, the rise of the Tea Party, the battles against Obamacare, the various showdowns on the debt ceiling and government funding, and the rebellion of the GOP base against its elites' immigration reformism.

In the interim, the wave elections of 2010 and 2014 have brought a new crop of Republican elected officials to power — officials who owe little or nothing to the Bush family, but who have learned that they'd better make sure not to get on the wrong side of their party's base.

And that party's base had no use whatsoever for John Ellis "Jeb" Bush. His support for immigration reform — which he, unlike Marco Rubio, never abandoned — and his ties to the GOP establishment made him an ill fit for this year's primary electorate, which has seemed to be in an anti-establishment mood.

Rubio's presence in the race was a huge problem for Bush from the start

But even as Donald Trump and other outsiders surged in the polls, Bush's team thought he still had a path to victory. That path involved knocking out the other establishment-friendly candidates in the race, so he could consolidate support among the party's more mainstream voters — and then, hopefully, win a head-to-head matchup with Trump or Ted Cruz.

The problem with that was named Marco Rubio.

From the start, it was clear that Rubio shared many of Bush's political strengths and had little of his baggage.

Bush hoped to use optimistic rhetoric to sell conservative principles, but Rubio does the same — and he's much more charismatic and a much better speaker than Bush.

Bush might have hoped that his Spanish-language fluency and Mexican-American wife could help him appeal to Latino voters — but Rubio actually is Latino.

Bush hoped to argue that he's more electable than Trump or Cruz — but how could he convincingly argue that nominating a Bush against Hillary Clinton would be better than nominating young, dynamic, fresh-faced Marco Rubio?

In addition to all this, Rubio has done a better job at appealing to the party's mainstream voters than Bush has — and he's also demonstrated potential appeal to its conservative voters, as a crossover candidate. For instance, Rubio managed to win 23 percent support in the Iowa caucuses, while Bush couldn't even pull 3 percent. Rubio is just a more appealing candidate.

The total failure of Bush's campaign shows money can't buy everything

In retrospect, the Bush 2016 operation was most notable for raising a massive amount of money — money that utterly failed to improve the candidate's prospects.

When Bush's team announced in July of last year that an affiliated Super PAC had raised more than $103 million — a massive and unprecedented sum for a primary — many of his rivals, including Hillary Clinton, were reportedly terrified.

But it turns out they shouldn't have been. Donald Trump surpassed Bush in national polls that very month, and would never fall behind him again. Then Ben Carson shot past Bush. Then Marco Rubio did. Then Ted Cruz did. And now even John Kasich has.

Naturally, Bush's Super PAC started spending tens of millions of dollars on ads promoting Jeb and savaging his rivals. But it was to no avail — the polls barely budged. It seemed like no amount of money could convince Republican voters to give Jeb Bush a shot.

Eventually, Bush tried to rejuvenate his campaign by taking on the new frontrunner, Donald Trump (who had memorably dubbed Bush a "low-energy person"). But nothing he tried there seemed to work either. He seemed to get the better of Trump in a few later debate exchanges, but Trump remained at the top of the polls, and Bush remained near the bottom.

It's an ignominious end to the Bush campaign — and perhaps the Bush family's political prominence overall. Both Republican politicians and Republican voters have simply decided to turn the page. As Marco Rubio likes to say: "Yesterday is over."