Pence will launch his campaign with a video and a speech in the early nominating state of Iowa, the sources said.
On June 1, Pence's polling average in the Republican field was less than 4%, compared to Trump's 53%, according to a RealClearPolitics average of polls.
Pence has continued to embrace many of Trump's policies, while portraying himself as an even-keeled and consensus-oriented alternative.
The success of his campaign will hinge on whether he can attract enough backers of Trump's policies who are turned off by the former president's rhetoric and behavior to build a viable coalition.
Reporting by Steve Holland; writing by Kanishka Singh and Tim Reid; editing by Tim Ahmann and Ross ColvinOur Standards: The Thomson Reuters Trust Principles.
Persons:
Mike Pence, Donald Trump's, Pence, Trump, Steve Holland, Kanishka Singh, Tim Reid, Tim Ahmann, Ross Colvin
Organizations:
Republican, Trump, U.S, Capitol, Christian, U.S . House, Thomson
Locations:
Iowa, Indiana, U.S