PPP’s newest Iowa poll continues to find a very close Republican race in the state- Donald Trump’s at 28% to 26% for Ted Cruz, 13% for Marco Rubio, 8% for Ben Carson, and 6% for Jeb Bush. No one else is over 3%- Chris Christie, Carly Fiorina, Mike Huckabee, John Kasich, and Rand Paul are all at that level followed by Rick Santorum at 2%, and Jim Gilmore at less than 1%.The race in Iowa is really remarkably steady- no one has seen their support shift by more than 2 points since our last poll a month ago.

The poll finds that the ‘birther issue’ has the potential to really hurt Ted Cruz. Only 32% of Iowa Republicans think someone born in another country should be allowed to serve as President, to 47% who think such a person shouldn’t be allowed to serve as President. Among that segment of the Republican electorate who don’t think someone foreign born should be able to be President, Trump is crushing Cruz 40/14.

Despite all the attention to this issue in the last week, still only 46% of Iowa Republicans are aware that Cruz was not born in the United States. In fact, there are more GOP voters in the state who think Cruz (34%) was born in the United States than think Barack Obama (28%) was. Donald Trump knows what he’s doing when he repeatedly brings up this issue- 36% of Cruz voters aren’t aware yet that he wasn’t born in the United States, and 24% of Cruz voters say someone born outside the country shouldn’t be allowed to be President. So this issue has the potential to be a difference maker with the race persistently so close in Iowa. The good news for Cruz is that when informed, 65% of Iowa Republicans say it makes no difference to them that he was born in Canada- but 24% saying less likely could be crucial in a margin of error race.

Beyond the birther issue there is plenty of good news for Cruz in this poll though. His 69/18 favorability rating makes him by far and away the most popular candidate in the state. In fact the only others over 60% are the relative nonfactors Mike Huckabee at 61/22 and Ben Carson at 60/25. Cruz is also the most frequently named second choice of voters at 21% to 13% for Rubio and 10% for Trump. Perhaps more importantly, among Trump voters specifically he is second choice for 39% to 11% for Carson with no one else in double digits. So if voters ever do get cold feet about Trump, Cruz is very well positioned to be the beneficiary.

There are some interesting divides in where Cruz and Trump’s support is coming from. Cruz leads 38/26 to 13% for Carson among voters who are most concerned with having a conservative nominee, while Trump leads Cruz 31/21 to 18% for Rubio among voters who are most concerned with having a candidate who can win the general election. Cruz crushes Trump 41/23 among voters identifying themselves as ‘very conservative’ but Trump is up 29/22 with ‘somewhat conservative’ ones and 31/11 with moderates. Cruz is up 35/21 with younger voters, but Trump is up 31/22 with seniors and 32/22 with middle aged voters.

The Obama birther issue is also a major dividing line and gives another prism into the extent to which Trump’s success is being driven by racism. Among people who think Obama was not born in the United States Trump is dominant, getting 38% to 23% for Cruz. But among non-birthers- either people who think Obama was born in the country or aren’t sure, Cruz is leading Trump 29/22. Similarly Trump leads Cruz 37/26 among the 52% of Republican primary voters who are offended by bilingual, but among the 40% who aren’t offended by them Trump is in only third place at 17% behind Cruz’s 26% and Rubio’s 18%. Trump’s success really is built on the support of the most intolerant segment of the GOP base.

Even with just three weeks left until the voting things remain pretty wide open in Iowa. Just 57% of voters say that they’re firmly committed to their current choice. The good news for Trump is that he has the most committed voters- 73% say they’re firmly committed to him compared to 58% for Cruz and Paul, and 57% for Carson. Everyone else has a majority of their voters open to moving to someone else. The bad news for Trump is that if supporters of the second tier candidates decide to shift to one of the top three candidates- or just to one of the top two candidates- it could be bad news for him. When you narrow the field to the top three Cruz leads Trump 38/32, with Rubio at 22%. And when you narrow it to a head to head, Cruz leads Trump 54/37. Supporters of all 10 of the other candidates would prefer Cruz over Trump if they had to pick just between those two. If much strategic voting goes on over the next three weeks it’s not likely to bode well for Trump.

A couple other quick notes on the Republicans in Iowa:

-Jeb Bush (26/54) and John Kasich (26/39) both have favorability ratings mired in the mid-20s.

-77% of caucus voters say Carly Fiorina’s rooting for Iowa in the Rose Bowl made no difference to them, and more than twice as many voters (15%) say it made them less likely to vote for her as (7%) say it made them more likely to vote for her.

-There’s pretty broad support among GOP voters for the most discussed recent gun measures. By a 73/17 margin there’s support for barring people on the terrorist watch list from purchasing a firearm. And by a 65/24 spread there’s support for requiring a criminal background check of every person who wants to buy a firearm.

Things are tightening up on the Democratic side. Hillary Clinton now leads Bernie Sanders 46/40, with Martin O’Malley at 8%. Clinton is down 6 points from her 52% a month ago, while Sanders is up 6 points from his previous 34% standing. The increased tightness of the race has a lot more to do with Sanders than it does Clinton. Clinton’s favorability is 72/22 this month after being 73/19 last month, a minimal change. But Sanders’ favorability has shot up from a 65/23 spread to now 79/13 so his popularity is clearly growing as the voting nears. The good news for Clinton is that 78% of her voters are firmly committed to her, compared to 64% of Sanders’ who say the same for him. Clinton’s lead goes up to 53/39 among those who have their minds totally made up.

O’Malley’s continued presence in the race is helping Clinton. In Iowa we find his supporters would prefer Sanders over Clinton 43/20, and in New Hampshire they prefer Sanders over Clinton 47/13. So to some extent O’Malley is helping to split the anti-Hillary vote.

There are some pretty big demographic divides in the Democratic race. Clinton leads 52/36 with women, but Sanders is up 46/39 with men. Clinton leads 64/26 with seniors, but Sanders is up 55/33 with younger voters. Clinton’s 47/38 advantage with middle aged voters pretty well mirrors the overall numbers.

Full results here