Written off by both parties, buffeted by a tornado of innuendo about his in-laws’ offshore gambling operation and hammered by millions of dollars of outside spending from Republican groups, Democratic Rep. John Tierney defied the odds and won a tight re-election victory Tuesday night in Massachusetts’ 6th district.

He beat former state Sen. Richard Tisei (R), who now joins a big group of Bay State GOP challengers who have fallen short. In fact, no Massachusetts Republican has won a seat in the House since 1994.

With 98 percent of precincts reporting, the Associated Press had Tierney taking 48.4 percent to Tisei’s 47.1 percent.

In the final months of the race, the narrative war was largely fought on Tisei’s turf, with ads from both sides focused on Tierney’s in-laws’ legal problems.

But on Election Day, the Tierney campaign — in concert with the state party and Senator-elect Elizabeth Warren’s campaign — pushed hard to turn out Democratic voters, particularly in Gloucester, Lynn and Salem. That well-crafted effort appeared to have paid off, pushing Tierney over the top after trailing in recent polling.