Patrick, in a statement Thursday, said: "After a lot of conversation, reflection and prayer, I've decided that a 2020 campaign for president is not for me."
Patrick's statement had been expected. Several sources had confirmed Wednesday that he would not run.
The 62-year-old Patrick served two terms as governor, from 2007 to 2015, was assistant attorney general for civil rights in the Clinton administration, and since leaving the governor's office has been a managing director for Bain Capital.
He traveled across the country in support of Democratic candidates in the recent midterm elections, raising his national profile.
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