Pro-family groups say the Senate's 49-48 vote against a constitutional amendment to protect marriage ignores the will of the majority of Americans. Sixty votes were needed to approve the amendment.

"Today the U.S. Senate voted against marriage and against the American people," said Family Research Council president Tony Perkins. "This Senate is grossly out of step with the American people."

Perkins pointed to the June 6 vote in Alabama which approved a marriage amendment by 81 percent, bringing the number of states with constitutional amendments protecting marriage to 20.

The Pennsylvania state House also approved a proposed constitutional amendment banning same-sex marriage June 6 by a vote of 136-61 that included significant Democratic support, reported the Philadelphia Inquirer. The approved proposal would define marriage as a union between one man and one woman. The bill will likely be voted on in the Senate by the end of June.

"These amendments have been enacted by an average of over 71 percent of the popular vote. An additional 26 states have statutes protecting traditional marriage," Perkins said. "That's 46 out of 50 states that have taken extra steps to define marriage as being between a man and a woman."

World Congress of Families organizer Dr. Allan Carlson expressed "extreme disappointment" over the Senate's failure to approve the Marriage Protection Amendment.

"The Senate has once again evaded its responsibility to defend the institution of marriage," Carlson said.

Carlson referred to the United Nations Universal Declaration of Human Rights, which recognizes the right of "men and women" - and men and women alone -- "to marry and to found a family."

"This suggests that the United States government has an absolute duty to keep the courts from defining marriage out of existence, as the Massachusetts Supreme Judicial Court did three years ago, when it forced gay marriage on the state," said Carlson.

The role of the courts are a matter of concern for pro-family groups. Judges in several states, most recently Georgia, invalidated voter-approved constitutional amendments to protect the definition of marriage as the union of one man and one woman. Courts in New Jersey and New York are poised to rule in cases that would make same-sex unions legal.