Why are some Republicans talking about a third party candidate?
There are those in the party who don't like Donald Trump, who don't trust him and think he is, in the words of one Republican establishment figure, "spectacularly unqualified to be president".
They can't quite bring themselves to vote for Hillary Clinton so would like a conservative alternative in November.
There are three things they can do.
They can get an existing minor party to field a candidate they can get behind; they can create a new party of their own; or they can back an Independent.
The leading figures behind this drive are commentators Bill Kristol and Erik Erikson.
But they have the support of others, including former Republican nominee Mitt Romney.
He launched a scathing attack on the Trump candidacy in March and urged party voters to do what they could to stop him.
That clearly didn't work.
Romney has ruled himself out for a slot. Ohio Governor John Kasich was considered but while he hasn't leapt to endorse Trump, he still harbours hopes of another presidential run.
Mark Cuban, a businessman, was considered too, but told the Washington Post "I don't see it happening".
The Bloomberg factor
Nebraska Senator Ben Sasse has been very vocal about the choice facing US voters this November, airing dissatisfaction about Trump and Clinton.
Still, he's not high-profile and would struggle to be picked out of a line-up in his home state.
No one has yet thrown up their hands and shouted "Pick me".
It's instructive that Michael Bloomberg, the mega-rich former New York mayor, apparently spent a lot of time and money looking at launching his own third-party bid.
He had name, recognition, a basic political operation and could throw a considerable amount of his millions into a campaign.
But while believing Bloomberg could win a few states, he realised he could not win the presidency.
There are a number of donors who do not want Trump to win, so they would be tapped to help when it comes to finances.
But it costs around $1bn to run a full-on presidential campaign. It's hard to see any third party raising a 10th of that.
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The filing deadline for the election has already passed in Texas. And other states will follow very quickly. So if they want someone in place, it really needs to be within the next two weeks.
In 1980, John Anderson did not declare his independent run until late April and through the courts managed to get on the ballot in all 50 states and Washington DC. He didn't do well.
Ross Perot pulled in nearly 20 million votes in 1992. That's 18.9 percent of the vote.
Republicans believe he took votes away from then president George Bush and handed the White House to Bill Clinton.
When he ran under the Reform Party banner four years later, he lost 12 million votes somewhere and virtually disappeared from politics.
The aforementioned Anderson ran in 1980. He polled nearly six million votes as Ronald Reagan won in a landslide.
Wallace and Nixon
In 1968, Alabama's governor, George Wallace, ran for the newly formed American Independent Party.
The man who once declared "segregation now, segregation tomorrow, segregation for ever" won almost 10 million votes and, crucially, 46 electoral college votes, all in the deep south.
Richard Nixon took the win but stole Wallace's law-and-order platform: a coded reference to the race riots many blamed on Black Americans and turned it into his successful southern strategy in 1972.
It's almost a 100 years since there was a credible third-party candidate.
Teddy Roosevelt running as the Bull Moose Party's nominee in 1912 captured 27 percent of the vote, taking second place and forcing the Republican into third.
So should Trump be worried? If they can get a credible candidate, and if they can raise the money, and if they can get that person on as many state ballots as possible, there might be a problem then.
But there are way too many "ifs" for him to start losing sleep.
Source: Al Jazeera