Massachusetts voters haven’t sent a Republican to the U.S. House of Representatives from any district in nearly 20 years. Republican Richard Tisei nearly broke that streak in 2012 and is challenging Rep. John F. Tierney, D-Mass., once again in 2014.  

Tierney’s vulnerability is specific. Massachusetts’ 6th District voted for Barack Obama with 55 percent in 2012 and 57 percent in 2008. But Tierney nearly lost to Tisei last cycle, 48 percent to 47 percent, with the help from a Libertarian candidate who received 4.5 percent. The Democrat’s wife and brothers in law have been in legal trouble, and that appears to have taken a toll on Tierney’s numbers. The congressman denies any wrongdoing.  

This year, Tierney faces Tisei once again, as well as two primary challengers: Marines Corps veteran Seth Moulton and attorney Marisa DeFranco. Democratic strategists are dismissive of the primary. They released a poll that showed the congressman with a 64 percent to 17 percent advantage and didn’t even offer DeFranco as an option.  

But Moulton had $651,000 in the bank on March 31 , so he isn’t going away quietly.  

Tisei is a top-tier challenger who will have to defend himself better from Democratic attacks that couple him with the most conservative members of his own party. This year will be a prime test as to whether voters have moved beyond the Tierney family’s issues.  

This looks like an excellent Republican opportunity, so we are changing our Rothenberg Political Report /Roll Call rating of the race from Lean Democrat to Toss-Up/Tilt Democrat .