Rep. Chris Murphy (D-Conn.) jumped into the 2012 Senate race Thursday, saying in a statement that he decided to run to offer "a fresh, progressive voice."

Murphy is the second Democrat to enter the race, just one day after Sen. Joe Lieberman (I-Conn.) told supporters he would not run for a fifth term. 

Former Connecticut Secretary of State Susan Bysiewicz (D) declared her candidacy earlier this week. 

"I've decided to run for the United States Senate in 2012 because I believe that I can be a stronger voice for the issues that matter to Connecticut, like creating good jobs and ending these costly wars, in the Senate," Murphy's statement read.

Murphy said entering the race was a "tough decision" but that ultimately, "what I've heard is that people feel that the Senate simply doesn't work anymore — it's become an unjustifiable barrier to positive change, and Connecticut needs a fresh, progressive voice there that will push for both policy and institutional reform."

The Democrat is heading back to Connecticut Thursday afternoon to officially launch his campaign at a 5 p.m. event in Cheshire.

Along with guaranteeing a Democratic primary for Lieberman's seat, Murphy's decision also means his congressional district could be up for grabs next year in an open-seat race that will likely be an early House target for Republicans. 

Bysiewicz welcomed Murphy's entrance Thursday, saying in a statement, "I look forward to a spirited discussion of the issues over the course of this campaign, focused on creating jobs right here in Connecticut."

A Bysiewicz internal poll shows her beating Murphy head to head in a Democratic primary 46 percent to 37 percent.   

-Updated at 2:45 p.m. and 3:36 p.m.