FARGO - North Dakota's congressional delegation says it wants an explanation of reports that some spectators were banned from President Bush's speeches on proposed Social Security reform.

Sens. Kent Conrad and Byron Dorgan, both D-N.D., requested an investigation of the matter in a letter sent Friday to U.S. Attorney General Alberto Gonzales and Treasury Secretary John Snow.

"These activities have no place in a free society, and would appear, at least on the surface, to violate the law," the letter said.

Rep. Earl Pomeroy, D-N.D., said he also has asked the White House for an explanation of the complaints, which have surfaced in at least two states.

"There's the appearance that it's standard procedure," Pomeroy said Friday. "I don't want this practice to continue into the future, and that's why I'm pursuing it now."

In February, a list of people banned from getting tickets to a Bush event in Fargo was published by the Forum.

The White House and the Republican Party denied such a list existed and Gov. John Hoeven's staff said no one was denied tickets. Police later said the list was created by a local volunteer involved in ticket distribution.

Last month, three people said they were singled out and removed from a Bush appearance in Denver, apparently because of their political affiliations. U.S. Secret Service officials said none of the agents responsible for protecting the president in Denver were involved with the group's removal.

White House spokesman Scott McClellan later said a diversity of views is welcomed at Bush's Social Security events.