Jussi Halla-aho, seen as leader of the far-right wing of Foreign Minister Timo Soini's Finns Party, will contest the party's leadership next summer.
Halla-aho, who has been a Member of the European Parliament since 2014, made the announcement on Monday afternoon via a video uploaded to YouTube and the party news site – which promptly crashed. He said that his main election theme will be immigration.
He positioned himself as an outsider compared to "the party elite". He said his main motivation is to ensure that the party has a "healthy" debate and genuine race before choosing a successor to long-term chair Timo Soini. So far several other candidates have come forth.
Halla-aho said in late December that he would run for Helsinki City Council in this spring's municipal elections and that he was considering a run for the party's top post next summer.
Within the last two weeks, party founder Soini announced that he would not seek re-election at next June's party conference, and the leader of the party's parliamentary group, Sampo Terho, has announced his candidacy.
"Catastrophic for credibility of the movement"
In the 18-minute video Halla-aho said: "Timo has led our party for 20 years, but he has never had a serious challenger. This kind of situation is not healthy, especially in a large party."
Halla-aho says the party's next chair should not remain in office for 20 years. Instead, he proposes a cap of three or four terms.
"It would be catastrophic for the credibility of Sampo Terho and the whole movement if he is applauded in as chair unanimously or by a crushing majority," Halla-aho asserted.
He said that Terho's credibility is already undermined by what he calls the "undisguised support of the party's elite....It looks strongly as though Terho is the crown prince, the candidate of Soini and the party elite".
Fined for ethnic incitement
Halla-aho, who holds a doctoral degree in linguistics, is thought to have the support of roughly one-third of the party's MPs. With 38 MPs, the party is the second-largest bloc in the Finnish legislature.
In mid-2012, Finland's Supreme Court found Halla-aho guilty of ethnic agitation and disturbing religious peace based on anti-Islamic and anti-Somali comments he had posted on his blog. He paid a small fine.
Halla-aho has served just over three years as a member of the Finnish Parliament, including a stint as chair of the Administration Committee. Immigration is one of many issues overseen by the committee.
Besides immigration, gun rights are another issue close to Halla-aho's heart.
On hearing that he had been assigned the candidate number 763 in April's local elections, Halla-aho wrote on Facebook that "nothing else comes to mind besides the calibre of a Mauser pistol". The 7.63mm cartridge was used in German Mauser C96 pistols.