Gov. Walker has become the first potential 2016 presidential candidate to open an office in Iowa, which will hold its GOP caucuses early next year.
Walker's fundraising group called "Our American Revival" has leased space outside Des Moines, in a building that other candidates' campaigns have used in prior years, including Mitt Romney and Michele Bachmann.
The news of the lease emerged, as the governor meets with leaders in Great Britain and, as the candidate watchdog group American Democracy Legal Fund filed a complaint against Walker's camp with the Federal Election Commission.
Fund director Brad Woodhouse says Walker's "Our American Revival" political organization, in testing the waters for a presidential run, may be raising and spending money that exceeds the limits the 1971 Federal Election Campaign Act imposed.