Politics produces some breathtaking ironies. When Ronald Reagan ran for re-election in 1984, polls showed that the second choice of his supporters, if he lost, was Jesse Jackson, a progressive Democrat and civil rights leader. Similar polling now shows undecided voters looking at Trump, Cruz and Sanders, who couldn’t be more different.

The reason is simple: A large bloc of voters wants big changes in government and the economy, and they’re looking for forceful and believable change candidates, regardless of their overall philosophy. That is exactly what catapulted President Obama to power in 2008 as the “change” candidate.

Former New York Mayor Michael Bloomberg has said he would run for president as an independent if Donald Trump and Bernie Sanders are nominated.

This year, Trump and Sanders are the leading change agents and the most successful candidates so far. They’re both critical of government and the economy, and their supporters all see the system as stacked against them.

They also lead in New Hampshire, where there are patches of thin ice for each of them to avoid. Late polling in Iowa showed a 6 percent decline in support for Trump after he failed to participate in last week’s final debate. Iowa voters didn’t like it any more than New Hampshire voters will like this week’s sore-loser whining from Trump that Cruz “stole” the election.

The loss in Iowa punctured Trump’s aura of invincibility, and his campaign was visibly leaking oil as it headed to New Hampshire. A loss or even a close race in New Hampshire, where he now holds a 25-point lead, would rip a gaping hole in the Trump myth machine and send his support into a free fall in upcoming contests.

A Sanders loss in New Hampshire would also be devastating, but it’s less likely. He’s a respected neighbor from Vermont and holds a comfortable lead there, without any damage coming out of Iowa.

If both insurgent candidates win in New Hampshire, the race will enter a far more difficult stage for them, with 16 red, blue and swing states elections between now and the Maine caucuses on March 5 and 6.

But it also will give them a fighting, if uphill, chance of become the nominee of their party. What happens after that is where this year’s irony comes in.

Sanders is saying some things that need to be said about the income redistribution that’s happened in America in recent decades.

But unless he can broaden his “revolution” from progressive 20-somethings to a true national movement, Republicans will savage him in a general election as a big spender and socialist, both of which he readily admits to. That will hurt him in swing states, particularly among blue-collar Democrats. And he won’t have the same firewall of support among women and minorities that Clinton has.

The prognosis for Sanders is that the top three or four Republicans would probably beat him, except for one. Sanders’ best chance to win the White House is for Republicans to nominate a vile, fragile lunatic. In other words, Sanders needs Trump to win his party’s nomination.

Trump has equally serious challenges in a general election, where his far-right positions will hurt him in swing states. Because of the demographics of those states, he’ll need to broaden his support from angry white men to at least a respectable number of women, blacks and Hispanics, which are groups where he’s now polling at record low levels.

Trump, in other words, will have almost no chance of beating Hillary Clinton.

For either Trump or Sanders to get the keys to the White House next January, they need to face each other in the fall.

But that would invoke another danger. Billionaire Michael Bloomberg says he’ll enter the race as a self-funded independent, should Trump and Sanders win, in order to save the country from what he sees as two extremists. That will be hard for him to do, practically-speaking, but not impossible.

Mainers understand better than anyone how that would throw the race wide open, with the possibility of any of the three winning in November. It would also present a terrible and dangerous scenario for the country. But those are columns for another day, if it ever comes, and I hope it doesn’t.

That kind of race would certainly put Maine on the national political map – we’re the leading laboratory of three-way races. I’d expect to see stories of Angus King and Paul LePage running in endless loops on network newscasts and journalists with notebooks and recorders crawling everywhere in the state.

Fortunately, that will only happen if both Trump and Sanders win their party’s nomination, which is still highly unlikely.

Alan Caron is the owner of Caron Communications and the author of “Maine’s Next Economy” and “Reinventing Maine Government.” He can be contacted at:

alancaroninmaine@gmail.com