Weld, who served as governor of Massachusetts from 1991 until his 1997 resignation to pursue an ambassadorship, has never hidden his distaste for Trump.
As the vice presidential nominee for the Libertarians last election, he hammered Trump and expressed support for Democratic nominee Hillary Clinton.
In a three-and-a-half minute announcement video, Weld's campaign touts his 1990 gubernatorial election victory in a Massachusetts that was "near bankruptcy" and under the influence of a "corrupt Democratic machine."
It highlights Weld's "guts, integrity, independence," and his efforts as U.S. attorney to root out government corruption. The video, which tells supporters that Weld's campaign begins in New Hampshire rather than Iowa, also touches upon Weld's tax cuts and welfare reform agenda as governor.
Though he is not popular broadly in the state, Trump enjoyed significant support among the Massachusetts Republican voters recently surveyed by Emerson Polling.
The incumbent claimed 82 percent support of potential Republican primary voters to Weld's 18 percent, though the poll was taken before Weld made his campaign official.