O'Fallon state Rep. Mark Matthiesen's family has relocated to Thailand, while the three-term lawmaker says he is staying behind in Missouri to continue his legislative duties. Matthiesen insists he remains committed to his district and is running for reelection in November, even as he prepares to spend at least seven weeks overseas with his family this year.
Matthiesen represents O'Fallon in the Missouri House, according to STLtoday.com, which first reported the family's move. He told the outlet he has done everything he can to support his family and has already visited Thailand multiple times, describing it as a beautiful country. He said he plans to return to the United States before turning his full attention to his reelection campaign.
A Democratic Challenger Raises Questions
Matthiesen is facing Democrat Gary Lester in the race for the seat. Lester, a retired chemist for a pharmaceutical company, said he's concerned about whether Matthiesen is actually living in the district — or even in the country — given the family's move. The station's report notes that Lester said he hopes Matthiesen does not resign if he wins reelection, warning that a resignation could force the governor to call a special election.
That concern isn't hypothetical in Missouri. Earlier this term, a wave of legislative departures left several House seats empty for extended stretches, and Lester pointed to that history as part of his worry about representation gaps if Matthiesen were to leave office mid-term.
A Pattern of Vacancies in the Missouri House
Former state Rep. Justin Sparks resigned from the Wildwood-based 110th District on November 24, 2025, to take a job with the U.S. Department of Homeland Security, according to stlpr.org. Sparks was in his third year representing the district when he stepped down. In his resignation letter, Sparks described joining DHS; in a separate Facebook post, he later wrote that he was returning to law enforcement.
As of that same date, there were five vacancies in the Missouri House, per stlpr.org's reporting. Vacancies have lingered before: in April 2022, six House seats sat empty, with the oldest dating back to April 21, 2021, according to Ballotpedia News.
What's Next for the O'Fallon Race
For now, Matthiesen's campaign plans remain unchanged on paper — he says he intends to keep running and to return stateside to focus on the November contest, even as his family stays settled in Thailand. Whether that arrangement affects his standing with O'Fallon voters is likely to remain a central question for Lester's challenge as the race moves forward.
