On the eve of the Massachusetts Senate special election, it's good to be Rep. Ed Markey. The longtime Democratic congressman is favored over former Navy SEAL Gabriel Gomez (R), with poll after poll showing him up comfortably.

Rep. Ed Markey (D). (Michael Dwyer/AP) Rep. Ed Markey (D). (Michael Dwyer/AP)

How did Markey seemingly -- it ain't over until it's over! -- avoid the fate of 2010 Democratic special election loser Martha Coakley? Here are the five biggest reasons:

1. The Democratic cavalry: After suffering that embarrassing defeat to Scott Brown (R), Democrats in Washington resolved not to fall victim again. The Democratic Senatorial Campaign Committee and now-Secretary of State John Kerry endorsed Markey early, helping him build on an already robust war chest and avoid a crowded and costly primary. After Markey dispatched of Rep. Stephen Lynch (D), Democrats kept their foot on the gas. The DSCC spent about $700,000 on TV ads. Majority PAC, a leading Democratic super PAC, bought airtime, too. Markey maintained a robust ground operation throughout the campaign, and to top it off, brought in the likes of President Obama and Vice President Biden to stump for him. In short, Democrats used everything in their toolbox.

2. National groups never showed up for Gomez: By comparison, Gomez never got serious buy-in from national groups. The National Republican Senatorial Committee says it spent some money (almost $1 million, the group estimates), but American Crossroads/Crossroads GPS and other GOP-aligned outside groups took a pass, and a super PAC supporting Gomez struggled to raise money. In the age of super PACs and nonprofits wielding major clout, candidates in competitive races are often only as good as the reinforcements they get. Gomez simply didn't convince national groups and donors coming off a bruising 2012 cycle that his underdog bid was worth a big-time play.

3. It's Massachusetts. 'Nuff said: As we've noted before, Brown's 2010 win can be chalked up to a confluence of factors that together helped him defy the state's strong Democratic tilt. Gomez didn't experience a similar wave. The state's strong Democratic tilt made Markey a favorite from day one, and it is one of the major reasons why he is in good shape heading into Tuesday. Another is that the race hasn't seized the attention of Bay State voters. More than one in four votes in a recent poll said they had little or no interest at all in the campaign.

4. No major Markey missteps: Part of the reason Brown won in 2010 was his opponent. Coakley made some big-time missteps. (Note: Dismissing the idea of stumping outside Fenway Park is never a good idea in Massachusetts.) The same can't be said of Markey. Few could argue that Markey is a very dynamic candidate. But it would be hard to make the claim that he self-destructed either. His campaign kept tight control over his message, and the result was a six-month stretch in which it would be hard to argue Markey made a major gaffe.

5. Gomez forced to play defense early: Democrats wasted little time after the primary going after Gomez. They hit him with accusations that he went too far with tax breaks he took on his home. At minimum, that aggressive strategy allowed Democrats to seize control of the conversation at a time when Gomez was trying to introduce himself to the universe of Bay State voters that had not paid attention to the GOP primary.

Updated at 2:12 p.m.