Mr. Pawlenty has been visiting early-voting states for months, recruiting contributors and courting activists who are influential in selecting the Republican nominee to challenge President Obama. He has struggled to break away from the party’s crowded field, so his announcement was intended to provide a head start raising money and building a campaign organization.

Image Tim Pawlenty, a former Minnesota governor, became the first candidate in the Republican field. Credit... Charlie Neibergall/Associated Press

“We need to encourage the dreamers and innovators,” Mr. Pawlenty said, “the small-business owners, the hard workers, the brave men and women throughout this country’s history that have asked for nothing more than the freedom to work hard and get ahead without government getting in the way.”

The development on Monday was the latest step in what has become a multilayered process of running for president. Even though Mr. Pawlenty had signed his paperwork on Friday, it was not delivered to the Federal Election Commission until Monday afternoon, when his advisers had decided to time the announcement for greater exposure.

He is the first of nearly a half-dozen Republicans who are expected to take steps to open exploratory committees, which allows candidates to raise money and hire staff members to test a presidential run. He is opening his campaign headquarters in downtown Minneapolis.

At this point four years ago, nearly 20 Democrats and Republicans had established exploratory committees or disclosed their intentions to run for president. Newt Gingrich, a former House speaker, is already raising money but has stopped short of filing an exploratory committee. Gov. Haley Barbour of Mississippi and former Gov. Mitt Romney of Massachusetts also are moving closer toward making their intentions known.