Conn. Senate candidates Chris Murphy and Linda McMahon are closer than ever in the upcoming battle for retiring Senator Joseph Lieberman’s seat, according to a new poll released Thursday by Quinnipiac University.

The poll suggests that Murphy, the Democratic candidate, is likely to receive 47 percent of the popular vote, just one percent less than McMahon, the Republican candidate for Senate.

This marks a shift from polls released last week that put Murphy several percentage points ahead of McMahon. It also represents a move from the Real Clear Politics average poll that put Murphy 2 percentage points ahead of his competitor.

The change is possibly a response to harsh ad hominem attacks by both parties, according to Douglas Schwartz, director of the Quinnipiac University poll. Murphy’s campaign has funded 1,564 television spots with negative advertisements, while McMahon’s campaign has sponsored 2,204. Unfavorable ratings have steadily increased for both candidates, a possible response to the negative advertising campaigns that have dominated the airwaves for the past several months.

Still, both Murphy’s and McMahon’s campaigns reiterated their personal attacks after reading the Quinnipiac poll.

“Linda McMahon is spending tens of millions of dollars on lies, smears and political attack ads in an attempt to distract voters from her strong support for right-wing Republican policies like ending Social Security, privatizing Medicare and giving millionaires like herself another massive tax cut,” said Murphy campaign spokesman Eli Zupnick.

Meanwhile, McMahon’s campaign manager Corry Bliss said the poll indicates that state voters are “wary of promoting a lifetime politician who failed to show up 75 percent of the time for his current $170,000-a-year, taxpayer-funded job.”

Bliss added that voters are not persuaded by the “nasty, false attacks Congressman Murphy and strong special interest supporters” have launched against McMahon.

The poll also found that 55 percent of McMahon’s supporters are “very enthusiastic,” while 39 percent are “somewhat enthusiastic.” Meanwhile, 27 percent of Murphy’s backers are “very enthusiastic,” while 55 percent are “somewhat enthusiastic.”

Only 46 percent of the eligible population cast a vote in the 2010 midterm election. For some, the closely-contested race is of national significance because decisions in a few key states will determine which political party controls the U.S. Senate.

This year, Senate elections will be held on Nov. 6, 2012.