McConnell was one of the main actors in brokering a deal after negotiations between President Obama and Speaker John BoehnerJohn Andrew BoehnerA warning to Ryan’s successor: The Speakership is no cakewalk With Ryan out, let’s blow up the process for selecting the next Speaker Race for Republican Speaker rare chance to unify party for election MORE (R-Ohio) stalled, but he worked closely with Vice President Biden to craft legislation palatable to both parties, which eventually passed the Senate with an 89-8 vote.

McConnell and Biden have worked together on deals numerous times in the past, during Biden's tenure in the Senate. But Benton's email makes no mention of Biden.

It says that though "well-intentioned allies in the fight for smaller government attempted to thwart President Obama's plan [...] it wasn't until Leader McConnell took the reins that real progress was made."

The bill ultimately did pass the House, but a majority of House Republicans voted against it, and many decried what they saw as a failure to include adequate cuts in a deal that relied, they said, too heavily on raising revenue to reduce the national deficit.

However, Benton says in the email that McConnell "has put us on strong footing in the fight to cut spending" with his deal.

The agreement brokered by Biden and McConnell extends Bush-era tax rates for a vast majority of Americans indefinitely, which Benton says takes them "off table" when Congress enters its next series of what will likely be equally contentious negotiations to increase the debt limit.

"Through his leadership, Senator McConnell has not only ensured that your taxes will not go up, he has taken the threat of income tax hikes totally off table for debt limit negotiations. Now, President Obama and his allies will not be able to threaten every American with higher taxes as we fight for spending restraint and entitlement reform," he says.

The email goes on to ask supporters for a contribution of "$50, $100, $250 or even $500 today."

At the end of September, McConnell posted more than $6.7 million cash on hand in his campaign coffers, putting him in a solid position for reelection in 2014. But McConnell could face a primary challenge from the Right, and Democrats also believe if they are able to recruit the right candidate he could be vulnerable going into reelection, as he was ranked as the nation's least popular senator in a recent poll, conducted by Democratic firm Public Policy Polling.

--This post has been updated to reflect the polling firm that conducted the survey.