Two Democratic senators denounced the National Security Agency for conducting "warrantless searches of the content of Americans' personal communications," and, more broadly, the senior government officials -- including President Obama -- who were "misleading" in denying that such searches took place.

"It is now clear to the public that the list of ongoing intrusive surveillance practices by the NSA includes not only bulk collection of Americans' phone records, but also warrantless searches of the content of Americans' personal communications," Oregon Sen. Ron Wyden and Colorado Sen. Mark Udall said late Tuesday.

The senators argued that the Fourth Amendment does not permit such searches, before focusing their ire on Obama's team for making "misleading" statements about NSA surveillance.

"Senior officials have sometimes suggested that government agencies do not deliberately read Americans’ emails, monitor their online activity or listen to their phone calls without a warrant," they said. "However, the facts show that those suggestions were misleading, and that intelligence agencies have indeed conducted warrantless searches for Americans’ communications using the 'back-door search' loophole in section 702 of the Foreign Intelligence Surveillance Act."

President Obama declared in January that the NSA does not listen to Americans' phone calls. "Let me repeat what I said when this story first broke," Obama said. "This program does not involve the content of phone calls or the names of people making calls. Instead, it provides a record of phone numbers and the times and length of calls, metadata that can be queried if and when we have a reasonable suspicion that a particular number is linked to a terrorist organization."

According to The Guardian, Director of National Intelligence James Clapper admitted that the NSA has conducted warrantless searches of Amercians' data that were lawfully collected as part of foreign surveillance efforts.

“There have been queries, using U.S. person identifiers, of communications lawfully acquired to obtain foreign intelligence targeting non-U.S. persons reasonably believed to be located outside the United States,” Clapper wrote in a letter to Wyden.