Democratic National Committee Chairman Howard Dean’s clarification this week that he has not officially endorsed Rep. Bernie Sanders (I-Vt.) in the open-seat Senate race illustrates the two Vermonters’ complicated relationship — the contradictions of which Republicans are eager to exploit.

DNC spokesmen were quick to point out that the former Green Mountain State governor was not endorsing Sanders when he made favorable remarks about the colorful Congressman to a Vermont newspaper Monday.

“Bernie is going to be an extremely strong candidate, but I think it is a little premature for me to endorse him right this minute,” Dean told the Rutland Herald on Tuesday.

Since becoming chairman, Dean has shunned the national media and will only do interviews with local news outlets.

Kind words from Dean and other national Democrats have sent GOP operatives digging through old press clips for the best quotes to demonstrate the animosity that previously existed between Sanders and Vermont Democrats.

Since their best hope, Gov. Jim Douglas, took a pass on the race, it is all Republicans can do to put chinks in the immensely popular Sanders’ armor until a GOP candidate emerges.

Sanders refuses to run as a Democrat, going so far as to turn down the Democrats’ nomination in his House races, and he got his start in politics as a socialist, sounding populist themes and bashing both parties for being beholden to special interests.

In a 1989 op-ed in the Burlington Free Press, Sanders accused both parties of being “intellectually and morally bankrupt.”

In his 1997 book “Outsider in the House,” the Progressive Caucus founder dismissed then-Gov. Dean as a “moderate-to-conservative” Democrat.

Sanders helped launch the Progressive Party in Vermont, even though he is not a member, and some Democrats have never forgiven him.

The two parties routinely run like-minded candidates for statewide races who then split the liberal vote and lose to Republicans.

Verbalizing Democrats’ frustration, Dean in 1996 told the Free Press that he never voted for Sanders and sometimes would leave the Congressional box blank on his ballot.

Despite that bit of defiance, Democrats routinely gave Sanders a pass in his eight successful bids for the state’s lone House seat.

The unofficial détente between Sanders and Vermont Democrats is now being tested, as he has made no secret of his desire to ascend to the Senate.

National Democrats seem content to treat Sanders, who caucuses with them in the House and posted a 98 percent party unity voting record last year, as one of their own, but state party officials have been reluctant to concede.

The internal debate about whether to field a strong challenger to Sanders next year continues among Vermont Democrats and has become part of the larger question of how Progressives and Democrats can work together to deny Republicans state and federal offices.

Most Democrats say that, after some hand-wringing, they will back Sanders, but that has not stopped local politicians from trying to reap gains from the chaos that has ensued since Sen. Jim Jeffords (I-Vt.) announced he would not stand for re-election.

Until there is a formal agreement, national Democrats likely will hold their tongues, awaiting the signal from Vermont, while Republicans will try to stir the pot by reminding Sanders and Democrats about why they disliked each other in the first place.

To wit, the GOP is circulating a 1993 Roll Call article in which Sanders lashed out at Vermont Democrats who were trying to prevent him from caucusing with their party in Congress.

“It is incomprehensible to me that the state Democratic Party would go out of its way to try to lessen my effectiveness in Washington,” he said at the time. “What an irony it is that [the leadership] have indicated a willingness to allow me to join the Democratic Caucus as an associate member, while retaining my status as an Independent, while Democrats in Vermont are opposed to that idea.”