Republican presidential candidate Mike Huckabee has called President Obama's guest list for Pope Francis' welcome this week "classless" and said the White House's decision to invite transgender activists, a gay bishop and supporters of abortion and euthanasia is a "new low for an admin that will go down as most anti-Christian in American history."

The guest list for an event at the White House's South Lawn to greet the pope on his first day in the U.S. on Wednesday includes Sister Simone Campbell, executive director of Network, a "Catholic social justice lobby" which supports abortion and euthanasia; Bishop Gene Robinson, former Episcopal bishop of New Hampshire who is the first openly gay Episcopal bishop in the country; Mateo Williamson, a former co-head of the transgender caucus of Dignity USA; and also activists from the LGBT group GLAAD, according to the Christian Post. The Vatican has reportedly objected to such guests, the Wall Street Journal recently reported.

"Classless decision by [the President] to transform [the Pope's] visit into a politicized cattle call is an insult to millions of Catholics," Huckabee wrote in a recent Twitter post.

"[The President's] show of disrespect for [the Pope] is a new low for an admin that will go down as most anti-Christian in American history," the former Arkansas governor continued. "Why is it that [the President] goes to extremes to accommodate Muslim terrorists but shows nothing but disdain for Christians?"

Huckabee also revealed he will appear alongside Megyn Kelly on Fox News Tuesday night at 9:30 PM ET/8:30 PM CT to further share his thoughts on the issue.

NPR reports that White House spokesman Josh Earnest responded to the criticism Monday, saying "there is no theological test that was administered prior to giving out tickets to stand on the South Lawn Wednesday morning."

Earnest also declined to respond to Huckabee's "anti-Christian" claim but said "There's plenty of opportunity for others to inject politics into this situation. It certainly is a protected constitutional right of theirs to do that. But that's not what the president is interested in."

Earlier, he stated that no one should draw any conclusions on specific guests "because there will be 15,000 other people there too."

"The diversity of the large crowd reflects the diversity of people in this country that are moved by the teachings and actions of this pope," Earnest continued.

Huckabee is not the only Christian leader to criticize the President's guest list: prominent evangelist Franklin Graham also expressed his disapproval in a Facebook post shared on Saturday: "This is disgraceful and obviously inappropriate," he wrote. "Is there no end to the lengths the president will go to in order to push his sinful agenda?"

Graham, who is president of the Billy Graham Evangelistic Association and Samaritan's Purse, said it is wise of the Vatican to "question President Obama's guest list" and that the list of guests "should raise a lot of eyebrows."