Long before the first polling places opened on election day 2016, the race for the 2020 Republican presidential nomination was already underway.

It has been unfolding in early primary states, where potential candidates have been introducing or reintroducing themselves. It has been on display in purple battlegrounds where they are helping in down-ballot contests. And behind the scenes, would-be contenders have sought face time with party power brokers eager to size them up.

"I think it's already happening now," said Congressman Tom Cole, a veteran GOP strategist. Cole identified another significant way the prospective candidates are laying a foundation: by embracing or shunning Donald Trump.

"You've seen some pretty dramatic reversals of people deciding they couldn't be for Trump and they are for Trump. Now, part of that to me is about positioning for presidential contests."


If Trump loses, Republicans will be forced to choose yet again from a full slate of ambitious candidates-in-waiting with wildly divergent visions for the party's future. Even if Trump wins, he will begin his presidency far from safe against the threat of a primary challenge, since an ample cross-section of his party has already spoken out against him.

A Trump win would also likely set off a potentially chaotic scramble on the Democratic side to field a challenger in four years. Democrats have failed to build a robust bench during Obama's presidency, in part because of the down-ballot drubbings the party has experienced in the midterms and partly because Clinton effectively froze the field as she considered her 2016 run.

No Republican has announced they are running in 2020 if Trump loses. Most have avoided even broaching the subject publicly, to avoid appearing presumptuous.

But interviews with more than a dozen Republican strategists, elected officials, donors and rank-and-file voters show that the party has already started pondering its future options and a recognition that the auditions have started.

Among the names most often mentioned are several failed 2016 candidates who eventually - and awkwardly - came around to supporting Trump: Senator Ted Cruz, Governor Scott Walker and Senator Marco Rubio.

Some see Governor John Kasich, who has held firm in his opposition to Trump after losing to him, as a possibility. Republicans are also intrigued by Senator Ben Sasse, an early Trump critic.

Trump's running-mate, Governor Mike Pence, also comes up frequently as a possibility if the 2016 ticket loses, as does Speaker Paul Ryan who has had a rocky relationship with Trump.

Republicans are also interested in some fresher faces, including first-term senators Tom Cotton, Cory Gardner and Joni Ernst and governors Nikki Haley and Greg Abbott.

Bobbie Kilberg, an influential Northern Virginia-based Republican fundraiser, said that she has already been approached by possible candidates seeking meetings after the election to lay out their visions for the future of the party. Kilberg declined to say who has sought her out.

"If Trump loses, I think it is very important that we do not again have eight to 10 highly qualified centre-right candidates running," Kilberg said, referring to the packed 2016 field. "We have to over time - not now, it's too early - coalesce around one or two maybe three people on the centre-right."

However, that lane appears to be no less clogged than it was four years ago. Kasich made a return to New Hampshire, an early nominating state no politician visits by accident. Rubio is up for re-election and a win would help wash away the stain of a stinging home state primary loss to Trump and give him new life in the party that some backers hope he will parlay into another run.

Cotton, a national security hawk who is an Army veteran of the Iraq and Afghanistan wars, spent time in Iowa last month. In the closing says of this campaign, he has hit the trail on behalf of GOP Senate contenders in tights races in Pennsylvania, Wisconsin and Indiana, a swing that could earn him some key allies down the road.

Trump's unlikely primary triumph, which came without early support from party elites, has emboldened many Republicans to push for an outsider again in 2020.

"If there's one thing that this campaign cycle has shown there is some competitive advantage for folks who are not viewed as being rooted in the establishment and the status quo," said former Ohio Secretary of State Ken Blackwell.

Cruz, who has clashed with party leaders, claimed an outsider mantle as he ran for president this cycle. But it fell flat against Trump and his pitch could face new obstacles if he runs in 2020. He only recently backed the nominee, months after declining to do so during a Republican National Convention speech that drew boos from many Trump supporters . Cruz's most immediate priority is winning re-election in 2018.

Ryan also has a near-term campaign that does not involve the presidency: winning re-election as speaker. Ryan's bid could provide a snapshot of his standing in the party after months of a turbulent relationship with Trump. It's also not clear that Ryan, who was the vice presidential nominee in 2012, wants to jump back into a lengthy national campaign.

One person whose name comes up among Republicans from different ends of the ideological spectrum is Pence, who has been a loyal and on-message running-mate for Trump. Pence is well liked by GOP leaders and Trump, too, making him something of a hybrid.

But whether Pence can energise Trump's base of loyal supporters remains to be seen. His style - soft-spoken and folksy - contrasts sharply with Trump's brashness and willingness to pick nasty fights with his own party, which drove his popularity in the primary.

Many Republicans say they don't expect Trump to step away from politics completely if he loses, nor do they expect his supporters to walk away form politics en masse. So the trajectory of the next primary could in fact rest heavily on how popular or unpopular he is in the lead-up to 2020.

But Trump's anti-immigrant, anti-Muslim rhetoric has worried many Republicans that his views are hurting the GOP's already struggling standing among minorities and putting the party further out of step with a swiftly diversifying country.

Some Republicans said a Trump loss could spur the party to walk down a path similar to one Democrats traversed after a third straight White House loss in 1988. In 1992, they nominated Bill Clinton, a centrist who won the election, helping the party reassert itself on the national stage and shedding the image that it was too liberal for mainstream Americans. That may be easier in theory than in practice for Republicans to replicate in their next primary.

"If you look at the Republican primary electorate compared to the Democratic primary electorate in 1992, the Republican primary electorate is more homogeneous and. . .much more ideologically skewed," said Emory University political scientist Alan Abramowitz.