But Democrats argue Blumenthals lead is much larger, and the DSCC released an internal poll this week that showed Blumenthal up 15 points.
Still, McMahons personal wealth has allowed her to run TV ads and introduce herself to voters, and it will let the NRSC allocate its finite resources elsewhere, said Quinnipiac University polling director Douglas Schwartz.
The seat was considered a safe seat for Democrats when Blumenthal got in, but Republicans have to be pretty happy because now its a competitive race, he said.
Similar to Connecticut, Republicans have a candidate who can self-fund in Wisconsin, where Republican Ron Johnson is challenging Democratic Sen. Russ Feingold. The NRSC has so far reserved $500,000 worth of TV time in the state.
Along with Missouri, Democrats are already on the air in Pennsylvania and Colorado, two states in which the NRSC has reserved time in October.
Vice President Joe Biden waits to conduct a mock swearing-in ceremony with Sen. Brian Schatz, D-Hawaii, in the Capitol's Old Senate Chamber, December 2, 2014. Schatz was sworn in to serve the remainder of his term since he was appointed to the seat after Sen. Daniel Inouye, D-Hawaii, passed away.