DOVER — Former congressional candidate Mike Miller announced Tuesday he is running again for the House of Representatives.

A small-business owner and Lewes native, he ran for the U.S. House as a Democrat in 2000, 2002 and 2008. He was defeated by incumbent Mike Castle, a Republican, the first two times and lost in the primary to Karen Hartley-Nagle in 2008.

He also ran unsuccessfully for the 6th Senatorial District in 2012.

Mr. Miller becomes the fourth candidate to announce for the open seat. For just the second time since 1992, there is no incumbent running for the position. Rep. John Carney, a Democrat, is campaigning for governor.

Two General Assembly members declared their candidacies in September. They are Sen. Bryan Townsend, D-Newark, and Rep. Bryon Short, D-Arden.

The winner of the Democratic primary will meet either Hans Reigle or Rose Izzo, the two Republican candidates.

The race could still get more crowded: Lisa Blunt Rochester, who served in the cabinets of both Govs. Tom Carper and Ruth Ann Minner, is also said to be considering a run.

“I’ve dedicated my entire life to creating economic stability for those in our community, so of course I am open to pursuing more ways I can continue the fight,” she said in an email.