Bob's blog: As militants advance, chaos in Iraq; Cantor loses primary in stunning upset

(CBS News) -- Anti-government insurgents in Iraq are currently sweeping towards Baghdad, and the ominous signs there raise a host of questions about President Obama's decision in 2011 to withdraw the majority of American troops. Obama announced Friday that his national security team was weighing different responses, and that he would make a decision "in the days ahead" on whether to take military action. In the meantime, Iraqi troops appear to have laid down their arms, taken their uniforms off, and left. All order has broken down. To be sure, taking Baghdad is not a done deal yet. It's going to be more difficult for the militants the closer they get to the capitol.

But when you look at what's happened, it's clear that Iraq has essentially come apart. This doesn't speak very well for the Iraqi forces. They were trained by the U.S. military, and that training apparently didn't work. I don't think very many people anticipated this. For a while now, it's been obvious that things in Iraq were not going very well, but this level of violence had not been anticipated.

The question now is: what can the United States do? We obviously can send in various kinds of equipment. But at this late date, getting equipment is not going to help all that much.

The big decision the president is going to have to make is whether the West should bring in some kind of air strikes. That is something that can be done not just by U.S. forces but by other American allies, as well. However, I don't think people are going to be rushing forward to help. This is going to take some persuading by the U.S. I think the next 24 to 48 hours are going to be crucial.

In an event like this, a lot of people say, "Why didn't we know?" There is going to be a lot of criticism about whose fault this was. Hillary Clinton was arguing yesterday that most of the fault could be placed on President Bush. But Obama has been in office for more than a term, so that's going to be a difficult argument to make. As is often the case, there is plenty of blame to go around.

We'll all be watching closely for signs that the president will order air strikes, since the militants are meeting no resistance as they move towards Baghdad. They've captured an enormous amount of territory. Within that territory are oil resources and a large amount of military equipment that the U.S. did not bring back.

On Sunday, we're going to talk to Sen. Lindsey Graham, R.-S.C, a member of the Senate Armed Services Committee. We'll ask him about the deteriorating conditions in Iraq, and we'll discuss the political landscape in the wake of House Majority Leader Eric Cantor's stunning primary loss. Viewers can also count on reporting from Iraq and Washington from our team of CBS News correspondents covering this story. Former Obama National Security Adviser Tom Donilon will be along to discuss the President's options.

We'll also talk to Republican National Committee chairman Reince Priebus about the fallout from Cantor's defeat. In addition, David Boies and Ted Olson will join us to discuss their new book, "Redeeming the Dream: The Case for Marriage Equality." The unlikely duo (Boies was the lead attorney for the Gore Campaign, Olsen for the Bush Campaign in the Supreme Court's 2000 Bush v. Gore case). This time, they teamed up and successfully worked together to convince the Supreme Court to overturn Proposition 8, which banned same sex marriage in the state of California in 2008.

Robert Costa of The Washington Post, Gwen Ifill of PBS, and CBS News Congressional Correspondent Nancy Cordes will round out our political panel.

We have two hugely important stories to work on this Sunday, so hope you'll join us.