His full remarks:

Yesterday, I updated the American people on the immediate steps we took, the increased screening and security of air travel to keep our country safe in the wake of the attempted terrorist attack on Christmas Day.

And I announced two reviews, a review of our terrorist watch list system and a review of our air travel screening so we can find out what went wrong, fix it, and prevent future attacks. Those reviews began on Sunday and are now underway.

Earlier today, I issued the former guidelines for those reviews and directed the preliminary findings be provided to the White House by this Thursday. It's essential that we diagnose the problems quickly and deal with them immediately.

Now, the more comprehensive formal reviews and recommendations for improvement will be completed in the coming weeks. And I'm committed to working with Congress and our intelligence, law enforcement, and homeland security communities to take all necessary steps to protect the country.

I wanted to speak to the American people again today, because some of this preliminary information that has surfaced in the last 24 hours raises some serious concerns. It's been widely reported that the father of the suspect in the Christmas incident warned U.S. officials in Africa about his son's extremist views.

It now appears that weeks ago this information was passed to a component of our intelligence community but was not effectively distributed so as to get the suspect's name on a no-fly list.

There appears to be other deficiencies, as well. Even without this one report, there were bits of information available within the intelligence community that could have and should have been pieced together.

We've achieved much since 9/11 in terms of collecting information that relates to terrorists and potential terrorist attacks, but it's becoming clear that the system that has been in place for years now is not sufficiently up to date to take full advantage of the information we collect and the knowledge we have.

Had this critical information been shared, it could have been compiled with other intelligence, and a fuller, clearer picture of the suspect would have emerged. The warning signs would have triggered red flags, and the suspect would have never been allowed to board that plane for America.

Now, the professionalism of the men and women in our intelligence, counterterrorism, and law enforcement, and homeland security communities is extraordinary. They are some of the most hard-working, most dedicated Americans that I've ever met. In pursuit of our security here at home, they risk their lives day in, day out in this country and around the world. Few Americans see their work, but all Americans are safer because of their successes.

They have targeted and taken out violent extremists. They have disrupted plots and saved countless American lives. They are making real and daily progress in our mission to disrupt, dismantle and defeat Al Qaida and other extremist networks around the world. And for this, every American owes them a profound and lasting debt of gratitude. Moreover, as Secretary Napolitano has said, once the suspect attempted to take down Flight 253, after his attempt, it's clear that passengers and crew, our homeland security systems, and our aviation security took all appropriate actions.

But what's also clear is this: When our government has information on a known extremist and that information is not shared and acted upon as it should have been so that this extremist boards a plane with dangerous explosives that could have cost nearly 300 lives, a systemic failure has occurred, and I consider that totally unacceptable.

The reviews I've ordered will surely tell us more, but what already is apparent is that there was a mix of human and systemic failures that contributed to this potential catastrophic breach of security. We need to learn from this episode and act quickly to fix the flaws in our system because our security is at stake and lives are at stake.

I fully understand that even when every person charged with ensuring our security does what they are trained to do, even when every system works exactly as intended, there's still no 100 percent guarantee of success. Yet this should only compel us to work even harder, to be even more innovative and relentless in our efforts.

As president, I will do everything in my power to support the men and women in intelligence, law enforcement, and homeland security to make sure they've got the tools and resources they need to keep America safe, but it's also my job to ensure that our intelligence, law enforcement, and homeland security systems and the people in them are working effectively and held accountable. I intend to fulfill that responsibility and insist on accountability at every level.

That's the spirit guiding our reviews into the attempted attack on Christmas Day. That's the spirit that will guide all our efforts in the days and years ahead. Thank you very much.

Rasmussen attributes Nelson's precarious position to his reluctant support for his fellow Democrats' healthcare reform legislation.

"Just 17% of Nebraska voters approve of the deal their senator made on Medicaid in exchange for his vote in support of the plan. Overall, 64% oppose the health care legislation, including 53% who are Strongly Opposed," the polling firm says.

It also appears Nelson would get at least a small boost if he shifted positions on the issue -- if he votes to block reform, the number of respondents who say they'd vote for Heineman drops to 47 percent, with 20 percent of those supporters now going to Nelson, who'd be at 37 percent.

It's not all bad news for Nelson, though: 2012 is a long way off, and there's still plenty of time for public opinion in Nebraska to swing away from the GOP. Plus, in three years, reform legislation is likely to be less of a front-burner issue.

These kinds of holds are often the sort of thing that senators like kept quiet -- hence the anonymous nature of many of them. DeMint's not one to do anything quietly, and he'd gotten coverage for this hold previously. But in the wake of the attempted bombing of Northwest Flight 253, he's getting some attention for the hold, and it's not a good kind of press for him or his fellow Senate Republicans.

Many major outlets have stories on DeMint's hold Tuesday -- the Washington Post has one, as does the Los Angeles Times. McClatchy has one, too, headlined, "Who's running the TSA? No one, thanks to Sen. Jim DeMint." Not the kind of headline anyone wants about themselves.

For now, DeMint's office says the senator won't drop the hold. But don't be surprised if you see some pressure from other Senate Republicans leading to Southers' confirmation soon enough.