SANTA FE, N.M. (AP) — Former New Mexico governor and current Libertarian U.S. Senate candidate Gary Johnson picked up the endorsement of Republican Sen. Rand Paul of Kentucky on Tuesday in his effort to unseat an incumbent Democrat.

Paul shunned Republican nominee Mick Rich, an Albuquerque construction contractor and newcomer to politics, in favor of Johnson, who was elected governor of New Mexico twice as a Republican before running for president in 2012 and 2016 on the Libertarian ticket.

Democratic Sen. Martin Heinrich of Albuquerque is seeking a second term in the November election.

Johnson and Paul share an enthusiasm for extremely limited government. In a news release, Paul praised Johnson as a "true fiscal conservative" and for his dedication to reducing the size of government and improving services as governor of New Mexico.

"His leadership on issues of government overreach, protecting Americans' Fourth Amendment rights against mass surveillance, and common sense foreign policy is sorely needed," Paul said in the statement.

Johnson backers are pressuring Rich to drop out of the race in the interest of ousting Heinrich. Tuesday was the final day for candidates in New Mexico to withdraw their names from the general election ballot.

Paul won't drop out, said his campaign spokesman, Nathan James.

Rich seized on the endorsement from Paul to highlight Johnson's support for recreational marijuana and to voice concern about hardline fiscal conservatism.

"New Mexico needs a senator who doesn't work to shut down the government, but who uses federal resources to help the people of New Mexico," Rich said in a statement.

Paul has waged a lengthy battle against federal deficit spending — triggering a brief government shutdown in February by holding up a spending bill vote from the Senate floor.