In a Monday email to donors, on the eve of Election Day, Moran touted the committee's work for Republican Gabriel Gomez in the race to replace Secretary of State John KerryJohn KerryFormer Obama officials say Netanyahu turned down secret peace deal: AP How dealmaker Trump can resolve the Israeli-Palestinian conflict John Kerry to teach at Yale on global issues MORE (D).

The committee spent nearly $1 million on the race in everything from transfers to the state GOP to spend on air to Web ads and polling. It's also deployed staff to the state and hosted fundraisers for the candidate.

Despite the effort, Gomez remains the underdog heading into the race's final days, with multiple polls showing Democrat Edward MarkeyEd MarkeyA guide to the committees: Senate GOP sets sights on internet privacy rules Overnight Tech: GOP chairman to propose high-skilled visa overhaul | Zuckerberg's 5,700 word letter | Tech lobbies gear up ahead of internet fight MORE ahead by double digits this past week.

Markey's persistent lead in the polls is in part due to the fact that he's outspent Gomez 3 to 1 on the air and received support from a handful of Democratic outside groups, while the Republican has had little help from outside GOP groups.

Gomez, a young Hispanic candidate with a background in business and the military, embodies the new kind of candidate party leaders proposed the GOP should pursue after its disappointing losses in 2012.

Some Republicans have expressed frustration at what they see as a hypocritical lack of support from the party's donor class.

But Moran's email attempts to make clear that the NRSC didn't leave its candidate out in the cold.

"We are extremely proud to have invested so heavily – and worked so hard – to elect a first generation American, Latino, Navy SEAL to the the US Senate from Massachusetts," he said. "We put our money where our mouth is, and our efforts have forced Democrats and liberal interest groups to spend millions upon millions in the bluest of blue states."

A smattering of polls throughout the race showed it to be within single digits, prompting Democrats to send in nearly every big name they have, including Vice President Biden, former President Clinton and President Obama.

Moran suggests that level of involvement doesn't bode well for the party's goal of maintaining control of the Senate, as they're looking to defend a number of incumbents in far less favorable states in 2014.

"If Democrats have to make that kind of effort, and heavily outspend Republicans by millions just to remain competitive in Massachusetts, how much will Democrats have to spend in states like Louisiana, West Virginia, South Dakota, North Carolina, Arkansas, Montana, Alaska, and New Hampshire?" he asks.