If Maine voters have one persistent electoral trait, it is that once they elect someone to a statewide office (including Congress), they are highly reluctant to reject that person later on.

Oh, it’s happened. Sen. Margaret Chase Smith was a fixture for four terms, but she finally concluded she didn’t have to campaign anymore.

Voters, diagnosing disrespect, replaced her with the obscure Second District Democratic Rep. William Hathaway, who so undistinguished himself in office that his successor in Congress, Republican Rep. William Cohen, easily defeated him six years later.

Meanwhile, Sen. George Mitchell went on to become Senate majority leader before retiring and turning his seat over to Olympia Snowe (a move that had some Democrats I know furious at him for a long time afterward).

In the First District, Rep. Peter Kyros, a Democrat, lasted four terms before being beaten by David Emery in 1974.

A possible reason that Kyros, a somewhat slippery character who had occasional run-ins with the law, was atypically defeated was because, a former Press Herald editorial writer told me, “More than half the people in the district finally got the chance to meet him.”

Another First District casualty was James Longley Jr., the son of the independent governor. Likely too conservative for the district, he lost his re-election bid to my college classmate Tom Allen.

But every other holder of the seat post-Kyros left it voluntarily, Emery to run for the Senate (and lose); John McKernan to run for the governorship (and win); former Gov. Joseph Brennan to run for his former office again (and lose); Tom Andrews to run for the Senate (and lose); Allen also to run for the Senate (and lose) — until finally we come to the current incumbent, Chellie Pingree, who, true to form, is in her fourth term.

The Second District seat after Cohen voluntarily retired was Snowe’s until she left it for the Senate, when she beat Andrews like a rented mule. Then John Baldacci used it to ascend (or descend) to the Blaine House, whereupon Michael Michaud held it for six terms until he unwisely retired to run for governor and was replaced by Republican Bruce Poliquin, who will himself win re-election if history holds true.

And with the exception of Gov. Longley, who kept his promise not to seek a second term, Maine’s governors have had no trouble winning twice in a row after the Maine Constitution was amended to permit two four-year terms.

Kenneth Curtis served the full eight years, as did Brennan, McKernan, Angus King (elected senator when Snowe retired in 2012) and Baldacci, while Paul LePage has half a term left to make it.

(At this point, I’m telling myself, “You’ve written a Jim Brunelle column” — because my former colleague, a politics and history buff and “Maine Almanac” editor whose column once occupied this Friday space, loved this stuff.)

All that, however, is prologue. Sen. Susan Collins, elected in 1996, easily won a fourth term in 2014 and seems destined to bask in perpetual voter approval.

However, Sen. King faces his first (and therefore most vulnerable) re-election campaign in 2018, when Gov. LePage is term-limited out of office. The governor has said a couple of times (retracting one reference “as a joke,” but not the other) that he would consider challenging King.

Where does one start? King is one of Maine’s most popular politicians, and Republicans would be hard put to unearth any other rival with LePage’s name recognition — or his hard-core support. Poliquin’s unlikely to challenge King, and the party will be focusing on a primary battle for governor that year.

So, considering how different our politics could look after this year’s presidential race, who’s to say where any advantage would lie?

Meanwhile, what will Democrats do? They, too, must find a gubernatorial candidate (preferably one who won’t pull a faceplant like Michaud’s). Cynthia Dill’s name gets mentioned, but she’s had some full-length frontal impacts of her own.

So, what’s on Rep. Chellie Pingree’s mind? If the House remains in Republican hands, will she grow tired of being in the minority and strike out for the Blaine House or the Senate (leaving her seat open for, perhaps, an ambitious legislative leader — or an equally ambitious mayor)?

My (wildly premature) guess? Well, since King is a Democrat in all but name, the party would be crazy to oppose him seriously. So if Pingree moves at all (a very open question), it will likely be for Augusta, not Washington.

But if the Democrats run any old doofus as a Senate placeholder, they risk siphoning votes from King. Could they give this race a pass and still remain a serious party?

Or — just maybe — could Angus be persuaded to swap his “I” for a “D”?

Jim Brunelle would be so proud.

M.D. Harmon, a retired journalist and military officer, is a freelance writer and speaker. He can be contacted at:

mdharmoncol@yahoo.com