Securing Joe O’Hern, a veteran field operative in the early-voting state, is a sign that the former Maryland governor is serious about taking on Hillary Clinton

Martin O’Malley is getting serious about challenging Hillary Clinton in Iowa.

While Clinton has already had more than 40 staffers on the ground since April in the state, which holds the first nominating contest in the Democratic primary, O’Malley has locked down one of Iowa’s top Democratic operatives.

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According to multiple Democratic sources, Joe O’Hern, a veteran field operative in the state, is slated to be the caucus director for the former Maryland governor in Iowa, a position which oversees voter contact. The Des Moines Register credited O’Hern with putting together “the largest field effort ever in a midterm election” for the Iowa Democratic party in 2014 and he also oversaw campaign efforts in the midwest for the Democratic Congressional Campaign Committee in 2012.

The operative joins Jake Oeth, a Des Moines-based consultant who served as the political director on Bruce Braley’s unsuccessful 2014 Senate campaign in Iowa. Oeth has been a consultant for O’Malley’s political action committee since the beginning of the year and is slated to be state director should O’Malley run for the White House.

O’Malley has long been active in Iowa, sending 11 staffers to the state during the 2014 midterm elections and making repeated trips to campaign for Democratic candidates. As the Maryland Democrat gears up for an expected launch of his presidential campaign at the end of May, the hire of O’Hern represents his most decisive step towards building a robust campaign operation that could potentially pose a threat to Clinton.

Spokespeople for O’Malley’s political action committee did not respond to multiple requests for comment.