As the 2012 U.S. Senate race enters the second quarter of 2011, the campaign contributions continue to roll in for three Democrats running for U.S. Sen. Joseph Lieberman’s seat. Lieberman announced his retirement in January.

State Rep. William Tong, D-Stamford, former Secretary of State Susan Bysiewicz and U.S. Rep. Chris Murphy are currently competing for the Democratic nomination for U.S. Senate in a state that has voted for Democratic senators for 24 years.

Tong, serving in the General Assembly since 2006, announced his plans to run for the open seat on May 8 with the hope of raising $350,000 dollars before his first fundraising quarter ended on June 30, according to a statement.

He surpassed expectations when he raised $550,000 in his first quarter, only 53 days after he declared his candidacy.

“I am grateful so many people believe in my campaign for the U.S. Senate, and have invested so much in so little time. This proves I am going to have the resources to run an aggressive campaign and win this race,” said Tong in a statement.

Murphy’s campaign stated second quarter contributions of $925,000, which brings their total since January to over $2 million.

Unlike Murphy‘s 2006 underdog victory against 24-year incumbent Nancy Johnson, he enters the U.S. Senate race as the frontrunner.

“Hitting the $2 million mark is great, but what I’m most proud of is that we continue to raise money the right way – from a quickly growing coalition of local, Connecticut donors,” said Murphy in a statement. “Amazingly, 1,141 of our donations during the second quarter were from first time contributors. I’m so grateful for this early strong support from so many people from throughout the state.”

Tong’s campaign said it won’t be able to report the number of contributors until next week.

Bysiewicz and her campaign manager won’t report her campaign’s second quarter numbers until the July 15 deadline.

Murphy and Bysiewicz secured more than three months headway on Tong when they stated their plans to seek nomination in the end of January.

During their first fundraising quarter, Bysiewicz raised approximately $500,000 but fell short of Murphy, who managed to raise $1 million.

One Republicans has declared their candidacy. Brian K. Hill, a Hartford lawyer and former Judge Advocate General’s Corps (JAG) officer who lives in Windsor, announced his Senate candidacy earlier this month as a Republican. He was an independent write-in candidate in 2010.

Former WWE CEO Linda McMahon, who spent about $50 million in a failed bid for the Chris Dodd’s former senate seat, still looms as a potential candidate.