But spokesmen for Republican state Rep. Dan Winslow and businessman Gabriel Gomez say Markey and Lynch are issuing more press releases and holding more congressional events in Massachusetts in a bid to win that seat. According to a report in the Boston Herald, the GOP candidates say that's an unacceptable way for the Democrats to boost their chances in the June election.

"This is an indefensible use of taxpayer money for political gain," said Will Ritter, a spokesman for Gomez. "That might fly in Washington, but it doesn't with the people of Massachusetts."

Charlie Pearce, a spokesman for Winslow, said that unlike the Democrats, Winslow is not using his current status as a state representative to boost his chances to win a seat in the Senate.

"Ed MarkeyEd MarkeyOvernight Energy: Trump set to sign offshore drilling order Sanders: Trump couldn't be 'more wrong' on climate Overnight Cybersecurity: Ex-officials warn 'Buy American' might harm Pentagon cybersecurity | Chair nudges Trump on cyber order | House gets security training MORE has spent almost four decades as a congressman amassing a multimillion dollar campaign war chest, which he is now using to underwrite his Senate campaign operation," Pearce said. "That type of political chicanery is why voters have such a lack of trust in Washington politicians."

The Herald reported this week that Lynch went from about one press release a month to more than 10 in January and February, while Markey has sent out 84 releases since he announced his Senate bid in late December.

Michael Sullivan, a former U.S. Attorney in the George W. Bush administration, is leading Winslow and Gomez in the race for the Republican nomination.

According to a recent poll, Markey is leading Lynch among Democrats by 35-24, although many Democrats are still undecided.