Jim Cole / AP, file

Former New Mexico Gov. Gary Johnson in Concord, New Hampshire, in October.

EXETER, N.H. -- Former two-term New Mexico governor and GOP hopeful Gary Johnson is dropping out of the Republican nomination race to run as a Libertarian candidate, NBC News has confirmed.

Johnson's campaign spokesman Joe Hunter cited Johnson's lack of exposure within the Republican party as a main reason for his decision to seek the Libertarian nomination.

Johnson appeared in only two of more than a dozen nationally televised debates and had trouble getting his shoestring campaign off the ground in early states. He will make an official announcement next Wednesday at a press conference in Santa Fe.

"His exclusion from the debates and lack of acknowledgement from the Republican establishment has been very frustrating," Hunter told NBC News. "His commitment since day one to get his message out."

Johnson's decision has been anticipated since he paused his New Hampshire-centric campaign several weeks ago.

His strategy shift notably began when Johnson nearly missed the registration deadline for New Hampshire's primary in October.

Johnson completed the filing with just hours to spare after a campaign staff mistake and a last-minute red-eye flight from Arizona to Manchester.

Several staff members left the campaign shortly afterward and Johnson quickly stopped canvassing in New Hampshire thereafter.

Johnson is known for his support for legalizing marijuana. He also supports abortion rights.

As New Mexico governor, he often worked with the Libertarian party to advance his agenda so this move is not entirely out of his comfort zone.

"Going back to his governor days, he has been comfortable with the Libertarian label," Hunter said.

The Libertarian party national convention will be held in Las Vegas next spring.