Sources close to U.S. Sen. Joseph Lieberman’s family said the four-term U.S. Senator won’t seek re-election in 2012, ending months of speculation about the Independent Democrat’s plans.

“While he enjoys being a Senator, he wasn’t looking forward to another two-year campaign cycle,” one source said.

Lieberman will make a formal announcement Wednesday at 12:30 p.m. in his hometown of Stamford.

The announcement comes on the heels of former Secretary of the State Susan Bysiewicz’s announcement that she will run for the seat.

U.S. Sen. Richard Blumenthal and Gov. Dannel Malloy were asked about the Lieberman’s retirement announcement at an unrelated press conference Tuesday evening.

Malloy quipped that it means Blumenthal will become a senior senator before the end of his first term.

“Senator Lieberman is the Senator from Connecticut for the next two years. We’ll be working with him and we’ll be working together with the rest of the delegation,” Blumenthal said.

Asked about Bysiewicz’s announcement, Blumenthal responded by saying, “You know I’m focused on doing my job. People are pretty tired of politics right now.”

Blumenthal said Lieberman had not contacted him to discuss his retirement and Malloy said his office may have received a call.

Lieberman, who ran as an Independent in 2006, began to fall out of favor with Connecticut Democrats over his support for the Iraq war. Adding fuel to the fire, the one-time vice presidential nominee supported Republican Sen. John McCain in the 2008 presidential contest, including speaking at the Republican National Convention. It was a move that caused Democrats in Connecticut to consider censuring him at the end of 2008. In the end, they opted to send Lieberman a strongly worded letter.

Meanwhile, Lieberman continued to caucus with Democrats in Washington even though he had become the swing vote on some contentious issues, including the national health care reform bill.

While some Republicans in Washington spoke about recruiting Lieberman, Republicans in Connecticut felt they could field a better candidate — possibly former wrestling executive Linda McMahon or Tom Foley, the businessman who ran unsuccessfully for governor in 2010.