Topeka ? The Kansas Senate on Saturday approved a proposed constitutional prohibition of gay marriages in what supporters of the ban called a stunning reversal brought about by political pressure from Christians across the state.

“A tidal wave of constituent demands has washed over the Legislature,” Sen. Tim Huelskamp, R-Fowler, said. “Thousands of concerned Kansans are demanding protecting of marriage statewide.”

Since March 25, when the Senate rejected a gay-marriage ban, numerous large Protestant churches and other religious groups have bombarded senators with letters and e-mails, urging them to resurrect the issue.

“I have seen evidence of the sleeping giant being awoken, and I rejoice in that,” Sen. Bob Lyon, R-Winchester, said.

The Senate approved the measure 27-13, by exactly the required two-thirds majority; it now goes to the House, which will consider it Monday.

If it is approved in the House by a two-thirds majority, 84 votes, then it will be on the November ballot for voters to decide. An earlier version passed the House in an 88-36 vote.

“I think it’s going to be very close,” said Rep. Paul Davis, D-Lawrence, who opposes the proposal. “I think there are some moderate Republicans who are going to change,” he said.

The proposal would amend the Kansas Constitution to say that the state recognizes only marriages between one man and one woman, and the state would deny the rights and benefits of marriage to any other kind of domestic relationship, such as a civil union.

The three-hour Senate debate on Saturday featured sharp rhetoric about historic family values from the Bible to “The Brady Bunch.”

Sen. David Adkins, R-Leawood, who led attempts to defeat the proposal, said the amendment would “embed discrimination” in the Kansas Constitution.

Urging his fellow Republicans to reject the measure, he compared it to laws passed in Nazi Germany that led to the Holocaust.

“This is a shame on the party of Lincoln. We should be better than this,” he said.

Sen. Mark Buhler of Lawrence, who has consistently opposed the proposed constitutional ban, was one of six Republicans to vote against it.

But several senators said they wanted to protect marriage as an arrangement between one man and one woman for the betterment of society.

Senate roll call on proposed marriage amendment More on the gay marriage debate in Kansas

“We have a body of research that shows that children fare best in a home where there is one woman and one man caring for them,” Sen. Susan Wagle, R-Wichita, said.

Lyon said he drew on the Bible for his guidance. “Civil law needs to be consistent with biblical law. I don’t think we should sanction immorality,” he said.

But opponents also quoted Scripture, saying that God wouldn’t want senators to judge and discriminate against their fellow man.

Others argued there was no reason to pass the constitutional ban because gay marriage is already prohibited by state law, and that lawsuits to challenge a constitutional ban will cost the state hundreds of thousands of dollars to defend.

State Sen. John Vratil, R-Leawood, served on the conference committee that drew up the language of the amendment, but voted against it and urged his colleagues to vote their conscience without regard to the political ramifications.

“This is not an issue on which you should decide based on your re-election prospects or the tally of your constituents. It’s not worth serving in this body if you can’t follow your heart and conscience,” he said.