Senate Minority Leader Harry Reid continued his push Tuesday for a bill to ban the sale of guns to Americans suspected of terrorism, even if the government can't show probable cause to a judge that Americans on the terror watch list are plotting terrorism. But Reid suggested it's "foolishness" for the government to listen to the phone calls of those same Americans on the terror watch list:

THE WEEKLY STANDARD: Leader Reid, if the government should be able to block gun sales to American citizens on the watch list without showing probable cause to a judge, should the government also be able to listen to the phone calls of people on the terror watch list without showing probable cause to a judge? REID: You've been taking too many cues from the NRA. The answer is: That's foolishness.

Legislation to ban individuals on the terror watch list from purchasing a gun is wildly popular, according to polls, but it also raises serious questions about due process rights of American citizens.

In December, Republicans offered an alternative amendment to the Democrats' terror watch list gun ban. The GOP measure, sponsored by John Cornyn of Texas, would block the sale of a gun for 72 hours and allow the government to deny the sale outright if it could show "probable cause" to a judge—the same standard needed to obtain a search warrant—that the suspect is plotting terrorism.

The Democratic bill relies on a lower legal standard to deny gun sales to American citizens. The measure, sponsored by Dianne Feinstein of California, simply allows the federal government to ban anyone on the watch list from buying a gun. The government's decision may be challenged in court by the prospective gun buyer, but the government's decision will be sustained if a "preponderance of evidence" indicates that the attorney general has a "reasonable belief" that the prospective gun buyer may be engaged in terrorism.

Several Democratic senators were unable to explain their objections to Cornyn's bill on Tuesday.

"I'd have to look at the Cornyn bill in greater detail," said Senator Richard Blumenthal of Connecticut. Asked if the government should be able to listen to the phone calls of Americans on the terror watch list without probable cause, Blumenthal ducked the question, saying, "I'm not going to deal with hypotheticals."

"I think we're going to be discussing that as the two bills come up," said Angus King of Maine when asked if a compromise was possible between the Republican and Democratic legislation. Neither King nor New Mexico senator Martin Heinrich would say if the government should be able to listen to the phone calls of Americans on the terror watch list without showing probable cause to a judge.

Democratic senator Jon Tester of Montana argued there is a "big difference" between the government's denying a gun sale without showing probable cause to a judge and listening to phone calls of those same suspected terrorists: "I'll just tell ya, this is a Montana farmer speaking: You don't get put on that don't-fly list for doing nothing."

"No, we should not listen to their phone calls," Tester told me. "The big difference is you listen to phone calls, that's done. ... You've already done it. You can get off a no-fly list and go buy an AK-47, okay?"

So is the Second Amendment less less important than the Fourth Amendment? "It's not at all," Tester replied. "That's a very, very unfair question. I don't want people blowing up people. If they're on the no-fly list, they screwed up."

Of course, it's possible for people on the terror watch list to blow people up with bombs, but Tester does not want to listen to their phone calls to find out if they're trying to build a bomb. And Tester's claim that all people on the watch list "screwed up" is false. There have been some high profile cases of innocent U.S. citizens—including former senator Ted Kennedy and The Weekly Standard's Stephen F. Hayes—being erroneously placed on the terror watch list.

The government certainly makes mistakes, but the number of people affected by either measure would be quite small because it's already illegal for most people on the terror watch list to buy guns. According to the National Counterterrorism Center, only 25,000 of the 1.1 million people on the watch list are U.S. citizens and legal permanent residents, and the Gun Control Act generally prohibits both illegal aliens and legal aliens who have "been admitted to the United States under a nonimmigrant visa" from buying guns.

On Tuesday, John Cornyn renewed a call to pass the legislation he introduced back in December. "I hope this week, perhaps, as we debate what the appropriate response is to dealing with these acts of mass terror, we look at the legislation that I introduced last December which would notify the FBI in the event someone on a watch list attempts to purchase a firearm and then give the FBI a chance, if the evidence warrants it, to detain that individual and to deny them access to the firearm," Cornyn said in remarks on the Senate floor.

Majority Leader Mitch McConnell raised eyebrows among the press corps when he suggested that he was open to "serious suggestions" on gun control. A McConnell spokesman confirmed he was referring to the Cornyn amendment. "We have been asking the administration for a serious plan to defeat ISIL, but in the meantime, Republicans haven't waited until this week to offer serious proposals. The Cornyn amendment from December is a good example—it got 55 votes, including two Democrats," McConnell spokesman Don Stewart writes in an email. "But we also just passed the defense bill, we passed a cybersecurity bill and are working on a series of tools to help the military, law enforcement and intelligence professionals find and defeat terrorists."

"In other words, we're working on solutions—not 30-second ads," he added.