Hartford - House Speaker Chris Donovan withdrew Thursday as a third-party candidate for Connecticut's 5th Congressional District, ending a bid for higher office that became mired in a federal campaign finance investigation.

The Meriden lawmaker, who lost the Democratic primary Aug. 14 to former state Rep. Elizabeth Esty even though he was the party-endorsed candidate, could have remained in the closely watched 5th District race because he was cross-endorsed by the Connecticut Working Families Party.

But some Democratic leaders opposed Donovan continuing to run as a third-party candidate, fearing he'd become a spoiler and ultimately help state Sen. Andrew Roraback, of Goshen, the GOP's 5th District candidate, win the seat being vacated by U.S. Rep. Chris Murphy, a Democrat. Murphy is now running for the U.S. Senate.

Donovan submitted a letter to Secretary of the State Denise Merrill on Thursday requesting that his name be withdrawn. Merrill said the Working Families Party has until Sept. 5 to nominate someone else if it wants to put a candidate on the November ballot.

Lindsay Farrell, the party's new executive director, said party officials have spoken with Esty several times about her positions on issues and had "some very productive conversations" with her. The party was expected to meet Thursday afternoon to decide whether to now endorse Esty in the 5th District race, enabling her to have her name appear twice on the November ballot.

The minor party has had concerns with Esty, who is considered more fiscally moderate than Donovan, on issues such as mandatory paid sick leave. She voted against paid sick leave legislation while she was in the General Assembly.

Farrell called Donovan "a champion for the values that affect the middle class and working class families" and said it was sad that his campaign became ensnared in a scandal over fundraising. Two of Donovan's former campaign aides were recently arrested and accused of conspiring to hide the source of $27,500 in campaign contributions to Donovan's congressional campaign. The contributions allegedly were tied to an effort to defeat state legislation to raise taxes on "roll-your-own" smoke shop owners.

The case remains under federal investigation. Donovan has denied any knowledge of the alleged scheme and has not been charged with any crimes.

Messages were left seeking comment with Donovan.

Farrell said she understands Donovan's decision not to continue running as a Working Families Party candidate. She has said he realizes he could inadvertently help Roraback get elected.

"He really wants to make sure the interests of average families in the 5th District are represented, and he thinks this is the best way to do it," Farrel said.

Donovan last week called Esty and urged her to reach out to the Working Families Party, backed by organized labor, and discuss where she stands on issues the party cares about.

Donovan will remain the House Speaker until his term ends in January.