A lot of Republicans would like Donald Trump to go away. But not too far. The prospect that Trump might eventually leave the primaries and run for president on his own has started to cast a shadow on the race, reviving memories of Ross Perot, Ralph Nader and the chills their third-party campaigns gave to Republicans and Democrats. Here are five things to consider as Trump refuses to rule out a third-party effort.

His standing

Polls this soon in the contest can be good at finding flavor-of-the-month favorites, not at judging who’s got staying power. Yet the polls this time are more than fingers in a fickle wind. They determine the 10, out of 16, who will attend the first debate on Aug. 6. Trump is surely in. As a billionaire who is paying for his campaign and not beholden to donors, Trump is also uniquely positioned to control his own staying power.

His politics

He’s very Republican on tax cuts and various other economic policies; not so Republican on health care, some social issues and more. He once favored a single-payer health care system, a big step beyond President Obama’s health care law. Records show Trump has given money to Republicans since 2010. Before that, one of the preferred candidates for his largesse was Hillary Clinton.

Perot-Nader effect

The odds are stacked against an independent becoming president. But those who try can change the dynamic of a race — and history. In the incredibly close 2000 election, Nader is widely considered to have tipped Florida and perhaps New Hampshire to Republican George W. Bush. In 1992, Perot drew support from both parties but many Republicans believe President George H.W. Bush suffered from Perot’s participation.

What's it take?

It takes a lot of money to make a consequential independent run. Trump seems to have it, although it’s not known how much he would be willing to spend. Longtime GOP donor Fred Malek estimates the cost of a serious third-party campaign at $500 million and doubts Trump would plow that much into an outside effort. GOP pollster Frank Luntz puts the cost at $200 million. “Trump can write that check today,” he said.

What's Trump say?

• “No. I won’t go on record as saying that.” July 18, on whether he would rule out a third-party bid.

• “Absolutely, if they’re not fair, that would be a factor.” July 22 about the option if the party mistreats him.

• “I want to run as a Republican.” July 23.

• “I would have no interest in doing that whatsoever. All I want to do is be treated fairly.” July 27.

Associated Press