OTTAWA -- John Baird says he'll step down as an MP as of Monday.

The former foreign affairs minister stunned political watchers last month when he resigned his cabinet post and said he'd be leaving politics entirely.

Baird's resignation from the Commons ends a political career that started when he joined the Progressive Conservative youth wing.

The 45-year-old was first elected to the Ontario legislature in 1995, and held a variety of posts in the Mike Harris Conservative government before jumping to the Commons in 2006.

In Ottawa, he became one of Prime Minister Stephen Harper's most high-profile ministers.

He held a variety of portfolios, including environment, transport, infrastructure and government House leader before becoming foreign affairs minister in 2011.

He announced his departure Wednesday on Twitter.

"After 20 great years representing my community I will be stepping down as MP on March 16. It has been an honour to serve."

Baird, with his roots in the Harris government, was one of the so-called blue Tories who supported the merger of the Progressive Conservative and Canadian Alliance parties.

He also supported Stephen Harper's bid for the leadership of the new Conservative Party of Canada.

When he first came to the Commons he was seen as a loud, two-fisted partisan, always ready to shout down the opposition, but he seemed to mellow as time went on.

"I quickly learned, though, to make a difference -- to really make a difference -- you can't be defined by partisanship, nor by ideology," he told the Commons after he resigned from cabinet.

"You need instead to be defined by your values."

New Democrat Paul Dewar acknowledged that sentiment at the time.

"As passionate as he can get, as partisan as he can get, and he can, he is also someone who reaches out," Dewar said. "He is also someone who understands the importance of getting things done."