Labor Day represented the traditional start of the presidential campaign, a long, arcane and seemingly interminable proceeding unique in the Western world — and almost as resistant to change as the Constitution itself.

Americans seem to like their candidates new and shiny, at least in the early going, and so it is that the presumed front-runners are looking a little shop-worn. Hillary Clinton bears the burden of having been an active national campaigner since 1992, while Jeb Bush is trying to become the third member of his immediate family to serve as president.

In time, Clinton’s other attributes may convince Democrats she deserves the nomination. The last three Democratic presidents, Jimmy Carter, Bill Clinton and Barack Obama, all came to the White House largely inexperienced and untried. Hillary Clinton’s eight years in the U.S. Senate and four years as secretary of state provide a level of experience unprecedented among Democratic presidents since Franklin Roosevelt.

It may help that her two most likely opponents, Bernie Sanders and Joe Biden, have been in politics even longer than she has.

It’s harder to envision a Bush climb back to the top. He, like the other 15 Republican candidates, has been relegated to the sidelines by the phenomenon of Donald Trump.

The Republican establishment has been trying to usher Trump offstage for months, to no apparent effect. In previous campaigns — the ones that elected George W. Bush and nominated John McCain and Mitt Romney — rabble-rousing was successfully marginalized. This time, Trump remains at center stage.

Up to now, the two main strands of contemporary Republicanism maintained an uneasy alliance. The Wall Street wing, which believes government is incompetent at everything and taxes must never be raised, remained dominant. The populist, evangelical wing that feels marginalized by demographic diversity stayed loyal even as the political mainstream moves elsewhere.

What’s loosely called the tea party took over the GOP ideologically in 2010, and Trump is the logical result. What even Mainers haven’t noticed yet is how closely he resembles their current governor. Trump is Paul LePage writ large.

LePage grew up in Lewiston, poor and later homeless, while Trump, in Queens, N.Y., was solidly middle class, his father a real estate developer. Yet their similarities are more compelling than their differences.

Neither LePage nor Trump knows how to compromise. Their idea of a negotiation is that they win. A more unsuitable attitude for American government, with its inherent and elaborate divisions of power, is hard to imagine.

When each is challenged, they double down. When LePage, having already convinced the Legislature to make unwisely large income tax cuts, became frustrated at having his latest plan rejected, he demanded abolition of the income tax. Filling in the resulting hole, amounting to half the state budget, is a detail that doesn’t interest him.

When Trump caught fire with Republican voters after vowing to build a 1,900-mile border wall with Mexico, he responded to criticism by demanding immediate deportation of an estimated 11 million immigrants without green cards. The roar for Trump increases as he takes on establishment icons, such as John McCain’s war hero status and Fox News’ dominance of the nominating process. There’s a lot of resentment out there, not all of it directed at the opposition.

LePage already has been elected — twice. It’s almost forgotten, but the final polls before the June 2010 primary gave Les Otten a comfortable lead among Republicans, with LePage in single digits. The tea party surge seemed to come from nowhere, and LePage was the beneficiary of weak and divided opposition that November to win with 38 percent of the vote. The opposition was no stronger in 2014, and LePage prevailed again.

In his second term, LePage is increasingly detached from any actual governing, sitting out the budget (again), inventing odd and non-constitutional views of his legal authority, and revenging himself on political opponents, such as House Speaker Mark Eves, and others who simply annoyed him, such as former Community College President John Fitzsimmons.

It’s likely an accurate preview of a Trump administration. Trump, like LePage, believes that his force of will is all that’s needed to solve political problems and satisfy the voters. It worked, after a fashion, for the two of them in business, but it was never going to work in elective office, where no one gets a free pass or is immune from criticism.

So if voters nationally want to imagine what it might be like to elect The Donald, they should take a close look at Maine state government over the past five years.

Douglas Rooks, of West Gardiner, has covered the State House for 30 years. Email at drooks@tds.net.