Candidates form exploratory committees to begin raising money and to assess the viability of their potential run for office.

The work of the exploratory committee formed by Connecticut Comptroller Kevin P. Lembo showed he could raise money and it did nothing to change the perception that he would be a strong candidate for the Democrat nomination for governor.

Yet on Aug. 31, Lembo made the announcement he won’t be running for that office.

In a phone interview last week, Lembo said the work of his exploratory committee also gave him a better idea of what a 2018 campaign for governor might look like. And that led to his conclusion he did not want to run for that office. Certainly not now. Maybe not ever.

“It became pretty clear in the last couple of weeks that my preference is always to go deep into the policy and work on the challenges I care most deeply about,” said Lembo. “In running for an office like governor, you end up skimming across a whole host of issues and not being able to go deep on any of them.”

OK, maybe.

My theory, however, is that Lembo made a clear-eyed political calculation that 2018 is going to be a tough year for a Democrat to win the gubernatorial race. After two terms of a candidate from one party, voters tend to want a change. Add in the repeated budgetary crises of the past eight years, the tax increases, and the laggard economy and that desire for giving the other party a chance increases significantly.

Lembo’s record has included initiatives to try to better manage the state’s underfunded pension fund for state workers, improving access to state financial records, and earning a reputation as an honest broker when it came to assessing the state’s budgetary health.

So it makes political sense for Lembo to run for re-election for a third term as comptroller. He will be the favorite. If re-elected he can continue working on those issues he said he feels most passionate about — the health care system and building greater stability into the state’s financial system to provide a foundation for economic growth.

In the process, he may build a record on which to run for governor down the line, perhaps against an incumbent who, like Gov. Dannel P. Malloy, will get beat up in trying to address the serious challenges Connecticut faces.

“You never want to say never,” said Lembo when I pressed him on the potential for a future gubernatorial campaign. “I know this is the right decision now.”

Exactly.

Lembo’s decision is bad news for the Democrats. Not that they can’t find another candidate to run, but because it is one more signal that this is the Republican’s race to lose. I just get the feeling that despite his misgivings about the superficiality of races for governor and his desire to “go deep” into issues, he would be running if the Democratic prospects looked better.

The Republicans could mess it up by nominating a candidate who pushes too far to the right. Such a candidate would make it easier for Democrats to capitalize on the one thing they have going for them — President Trump. The more Democrats can link the Republican candidate to Trump the more they can juice up the nonpresidential-year turnout in Connecticut’s largely Democratic cities and the greater their chances of returning a Democrat to Hartford.

In other words, Republicans should choose a moderate. But there will be a primary. And primaries attract more ideological voters on the left and right. And they don’t like moderates. If Republicans let this slip away, that will be the reason.

Paul Choiniere is the editorial page editor.