The Massachusetts special election to fill the U.S. Senate seat that was held for 46 years by the late Edward Kennedy will likely produce another Democratic senator.

Massachusetts is, after all, a very blue blue state that has not elected a Republican to the Senate since 1972 — and the winner that year, Ed Brooke, was every bit as liberal on most issues as the Democrat the state backed for president: George McGovern.

But the fact that likely is the right word, as opposed to certainly, explains why Democratic party and union strategists are rushing to bolster the candidacy of their candidate, Attorney General Martha Coakley, in a race with an attractive Republican, state Senator Scott Brown.

Massachusetts Senator John Kerry took the lead in ramping up the fear factor. The 2004 Democratic presidential nominee emailed Democratic donors on Monday with the message that:

This is our wake-up call. Polls in Massachusetts are tightening, and one even shows a dead heat in the fight to keep Ted Kennedy’s seat in the hands of a Democrat who will fight and vote for jobs, health care, clean energy and mainstream values.

The far right has launched a massive online fundraising effort, and Brown’s allies are blanketing Massachusetts with anonymously funded, shadowy attack ads by outside groups. Sound familiar?

It’s time to stand with Martha Coakley. Your donation now could make the difference. Election Day is in one week. Can you step up? …

The next five days will decide the fate of Ted Kennedy’s seat. Do we elect Martha Coakley — who will fight for jobs, our families and our communities as my Massachusetts colleague and the state’s first woman senator, or Republican Scott Brown, whose allies in the right wing dream of holding a “tea party” in Kennedy country?

Click here to donate $5 or more to the DSCC today. The special election is only a week away, and we need to raise $225,000 to fight the attacks, organize the grass roots and get each and every Democrat to the polls. Your donation now will make a difference!

Ads are running, phones are ringing, and volunteers are knocking on doors. Now is the time to push harder. We can’t leave anything to chance. Too much is at stake.

Republican strategists were chirping with delight about the prospect that a political turbulent moment would produce a game-changing upset: “The reality is, though, that the Democrats have reason to be worried. They know that if they don’t win this race by … double digits in a deep-blue state like Massachusetts, it will send shockwaves across the political spectrum.”

Fair enough. But what do the polls say?

While a Public Policy Polling survey conducted earlier this month had Brown one point ahead of Coakley, the well-regarded Boston Globe poll — which was conducted last week and released Sunday — had Coakley at 50 percent, Brown at 35 percent and libertarian independent Joseph Kennedy (who is not one of the Kennedys) at 5 percent. Nine percent of respondents were undecided.

Coakley’s actual margin could be wider.

As the Globe noted in its Sunday report:

Coakley’s lead grows to 17 points – 53 percent to 36 percent – when undecideds leaning toward a candidate are included in the tally. The results indicate that Brown has a steep hill to climb to pull off an upset in the Jan. 19 election. Indeed, the poll indicated that nearly two-thirds of Brown’s supporters believe Coakley will win.

“She’s simply better known and better liked than Brown,” said Andrew E. Smith, director of the University of New Hampshire Survey Center, which conducted the poll for the Globe.

But the race is still real.

And that has horse-race pundits and win-at-any-cost Democrats speculating about whether Coakley made a mistake when she demanded that every candidate who was on the ballot be included in what have turned out to be spirited pre-election debates. Brown wanted a one-on-one debate with the Democrat, but Coakley insisted that Kennedy — whose anti-tax, anti-war campaign could appeal to both Republicans and Democrats, and whose name might have been confused with that of former democratic Congressman Joe Kennedy — have a place on the panel.

The grumbling got so loud that, when the candidates debated Monday night, moderator David Gergen asked Coakley if she regretted her decision to give a forum to an independent candidate.

“I think it was a very good decision and I think that Joe, as you can see tonight, has added a lot to the debate,” replied Coakley. “People who are on the ballot should be able to get up when it’s a public-sponsored debate and have voters judge them as they would Scott or me or anyone else who gets signatures to get on the ballot.”

Coakley’s right, on several levels.

First: Kennedy certainly held his own in the debates, and actually pushed what would otherwise have been bitter, personality-focused fights in interesting issue-oriented directions.

Second: Including Kennedy in the debate removed any doubt about his family ties and let him appeal on his own merits. That probably helps Coakley, as it should pretty much eliminate the prospect that older Democrats might cast nostalgia votes for a a candidate with the same last name as the late lion of the Senate.

Third: Whatever her motives, Coakley deserves at least a measure of credit for erring on the side of an open process — something that at least some of her supporters argued against doing.

Debates should always include all the candidates who are on the ballot and have a chance of winning.

Since 1992, I’ve argued for the inclusion in presidential debates of every candidate who is on enough state ballots to win the 270 electoral votes needed to become president.

Ultimately, major-party candidates and their handlers ought not be in a position to decide whether credible independent and third-party candidates take part in debates. But, more often than not, the front-runner gets to make the call.

Coakley made the right call.

Brown, by trying to exclude the independent candidate from the debate, erred against an open democratic discourse. That doesn’t exactly position the Republican as the “change agent” his supporters imagine.