LINDA WERTHEIMER, HOST:
It's been a big week in politics. Presidential hopeful Donald Trump again said something many found offensive, and yet, instead of losing popularity, he went up in the polls. But then Senator Ted Cruz went ahead in polling in the all-important early state of Iowa. To talk about what's happened this week, I'm joined by NPR's national political correspondent Mara Liasson. Good morning, Mara.
MARA LIASSON, BYLINE: Good morning, Linda.
WERTHEIMER: So now before we get into Trump and his ups and downs, let's talk about what President Obama said about the climate agreement. He credited much of the progress and success of the agreement to the United States. How's Congress going to react to this?
LIASSON: Well, the treaty's goals are not legally binding. Actually, it's not a treaty. It's not a formal treaty. So they can't actually stop the treaty itself - the agreement itself. But Congress has the power of the purse and they have control over the money for that fund for smaller countries trying to adjust to climate change. Congress - Republicans in Congress are also trying to block the president's new regulations on coal-fired power plants and other programs designed to reduce the U.S. production of greenhouse gases.
WERTHEIMER: OK, onto the GOP. What do you make the new Iowa poll that shows Senator Ted Cruz 10 points ahead of Donald Trump in that state?
LIASSON: Well, that's pretty extraordinary. This is the Des Moines Register poll, conducted by J. Ann Slezer. It's considered the gold standard of polling. It's usually correct. We also have a new Wall Street Journal poll out today that shows nationally Cruz is in second place. Ben Carson is fading. And I think this - what this tells us is that the race is changing. The dynamic of the race is changing. Trump's still on top, Cruz now in second. The question is, will we see a Cruz-Trump battle?
WERTHEIMER: Do you think that this beginning to move, switch around kind of stuff started happening because Republicans in Congress pushed back? I'm thinking of House Speaker Paul Ryan who said that Trump's desire to bar all Muslims from coming to the U.S. does not represent conservative values.
LIASSON: I don't think Cruz is surging because of the criticism against Trump from Republicans. Certainly in Iowa he's been working very hard to organize evangelicals and tea party supporters. I think the criticism of Trump from the Republican establishment this week was because they see Trump as a big problem for the party. If he's nominated, he could hurt their chances, they think, to get the White House, and also down-ballot, the Republican Senatorial Campaign Committee has been instructing their candidates what to do if Trump is the nominee. The RNC is preparing for a floor fight at the convention if no one comes - gets to July with enough delegates to win. But really, Republicans, at least establishment Republicans, are not quite sure what to do because straightforward attacks on Trump tend to backfire. You saw that this week when his support went up. And you also see the Republican candidate reaction to Trump very mixed. The toughest criticism comes from the ones in the single digits, like Jeb Bush and Lindsey Graham with nothing to lose.
WERTHEIMER: So where do we go from here?
LIASSON: We go to Las Vegas. We're having a debate, a Republican debate, CNN debate, on Tuesday night. All the Republicans will be asked if they still stick by their pledge to support whoever the eventual nominee is, including Trump. Ironically, that pledge was designed to keep Trump in the fold. They don't want him to run as a third-party candidate. The question is - and we might find out the answer on Tuesday - is are Republicans willing to put up with Trump's xenophobia in order to avoid alienating his supporters? And that's a real concern because 68 percent of Trump supporters say they would support him if he broke off and decided to run as an independent. And Trump has been talking about doing that a lot more lately.
WERTHEIMER: National political correspondent Mara Liasson, thank you very much.
LIASSON: Thank you. Transcript provided by NPR, Copyright NPR.