Tierney has not been accused of criminal wrongdoing. In October 2010, his wife, Patrice, pleaded guilty to “willful blindness” of her brothers’ illegal gambling activities and served 30 days in jail.

The eight-term congressman faces a tough reelection bid against former state Sen. Richard Tisei. Republicans are hopeful they can capture the seat. The GOP doesn't hold a House seat in the deep-blue state of Massachusetts.

Tisei, an openly gay, abortion-rights-supporting Republican, has hammered Tierney about what he knew and when.

“People are very concerned,” a Democratic consultant, who wished to remain anonymous, told the Globe. “They have been for months, and nothing that’s unfolded in the last weeks has surprised anybody.”

Tierney said Tisei is trying to use his family’s criminal troubles for his own political gain.

“This is his only trick,” Tierney said of his GOP rival.

Tierney is considered a up-and-comer in Democratic politics. He was mentioned as a possible Senate candidate for the special election after Sen. Edward Kennedy (D-Mass.) died, and was also said to be considering challenging Sen. Scott Brown (R-Mass.) this cycle. He had a tough race in the 2010 election, which took place shortly after his wife's legal problems, but he won with 57 percent.

The Hill rates this race as lean-Democratic.