Former New Mexico Gov. Gary Johnson on Monday criticized President Barack Obama and Rick Santorum for their opposition to gay marriage.

Johnson, who earlier dropped out to the GOP presidential nominating contest and is currently running as a Libertarian Party candidate for president, struck out at his rivals in a statement published on his campaign website.

“Rick Santorum's position is unconstitutional,” Johnson wrote. “The Constitution requires that all citizens be treated equally and makes no reference to gender in assuring those equal rights. By any fair measure, equal access to marriage for all Americans is a right – guaranteed by the Constitution.”

Johnson, a supporter of marriage equality, criticized Santorum's recent remarks suggesting that gay marriage would open the door to polygamy.

“Senator Santorum's claim that legally recognizing gay marriage would be no different than legalizing polygamy, child molestation or bestiality is repugnant and insulting to millions of gay Americans.”

Johnson also criticized Obama for sending out “surrogates to imply that he will support gay marriage in a second term.”

“I, for one, am tired of seeing candidates for presidents – including the President himself – play political games with people's lives and happiness. Perhaps it's time for a president who leads based upon principle instead of polls.”