While a date has still to be confirmed for the contest, which follows the sudden resignation of Mike Hill on March 16, the Social Democratic Party (SDP) “is pleased to announce that we will be fielding a candidate”.
SDP leader William Clouston said: “In this by-election, the SDP wants to give the people of Hartlepool the electoral choice they've been denied so far: a patriotic and culturally traditional party that believes in investing in industry and communities.
“For too long, the Labour party has systematically ignored the concerns of Britain's working class and communities like Hartlepool.”
He added: “Neither can the Conservatives present a viable alternative to Hartlepool, with their party wedded to broken Thatcherite economics and the politics of inequality.
“On election day, only the SDP will be fighting for the real interests of Hartlepool: more industry and jobs, law and order in the community, and well-funded and well-run public services.
"Together we will break the stranglehold of the two-party system and make sure Hartlepool is represented by and for its people.”
Other parties to say they will take part in the by-election include the Northern Independence Party, which would be fielding its first Parliamentary candidate, while town businessman Samantha Lee is gauging public support before deciding whether to stand or not as an independent candidate.