First Read is a morning briefing from Meet the Press and the NBC Political Unit on the day's most important political stories and why they matter.

Trump and Cruz are ahead. That’s a nightmare for GOP establishment

After a slew of new polls over the past 48 hours, including from our latest NBC/WSJ poll, here is the unmistakable conclusion with seven weeks to go until the Iowa caucuses: Donald Trump and Ted Cruz are your co-front-runners in the Republican race. And that is a potential nightmare scenario for the GOP establishment -- because it might be able to sink one of these candidates but probably not both. What’s more, the national NBC/WSJ poll shows Hillary Clinton besting both Trump and Cruz in hypothetical general-election matchup, but losing against Marco Rubio and Ben Carson. Nationally, our NBC/WSJ poll shows Trump ahead of the GOP horserace at 27% among GOP primary voters (up four points since late October), and he’s followed by Ted Cruz at 22% (up 12 points!!!), Marco Rubio at 15% (up four), Ben Carson at 11 (down 18!!!), and Jeb Bush at 7% (down one). In Iowa, meanwhile, the Des Moines Register/Bloomberg poll has Cruz ahead at 31%, Trump at 21%, Carson at 13%, and Rubio at 10%. And another poll of the Hawkeye State, via Fox News, has it Cruz 28%, Trump 26%, Rubio 13%, Carson 10%. In a world without Donald Trump, there would be a Stop Cruz movement. But now the GOP establishment has to pick its poison. One other thing: Trump has now moved the window where Cruz looks moderate by comparison.

Why Cruz has maybe the easiest path to the GOP nomination

Last week, we called Cruz your “invisible GOP frontrunner.” But this week, we’re now confident enough to say this: He might have the easiest path to the GOP nomination. Think about it -- he wins Iowa, he wins South Carolina (an Iowa win would maybe make him the frontrunner there), and he’s set up for success in the March 1 “SEC Primary” states of Alabama, Arkansas, Georgia, Oklahoma, Tennessee, and Texas. (Yes, we know Oklahoma is Big 12 country, but it has a lot in common, politically, with those other states.) And we’ll say it again: Cruz wouldn’t have this easier path without Donald Trump.

But Hillary tops Trump and Cruz, but loses to Rubio and Carson

So heading into tomorrow’s GOP debate, it’s Trump-Cruz, Cruz-Trump. But according to our new NBC/WSJ poll, Hillary Clinton beats both in hypothetical general-election matchups.

Clinton 50%, Trump 40%

Clinton 48%, Cruz 45%

But Clinton loses to Rubio and Carson:

Rubio 48%, Clinton 45%

Carson 47%, Clinton 46%.

Christie, Paul make main debate stage

Meanwhile, heading into tomorrow’s GOP debate in Las Vegas, “New Jersey Gov. Chris Christie gained spot back on the main stage in the next Republican primary debate, while Kentucky Sen. Rand Paul protected his entry with a last-minute poll performance, CNN announced Sunday. Front-runner Donald Trump will once again take center stage during the main debate with four candidates on either side of him, the host network for Tuesday's debate said. Neurosurgeon Ben Carson and Texas Sen. Ted Cruz will be directly next to the former reality show star, while Ohio Gov. John Kasich, and Paul are positioned on the outskirts. Paul held on to his seat in the main debate due to a Sunday Fox News poll that placed him 5th in Iowa.”

Rubio vs. Cruz

While the political world is playing up some of the (minor) jabs between Trump and Cruz, the real action in tomorrow night’s debate might be Rubio vs. Cruz. We got a taste of it in Rubio’s appearance on “Meet the Press” yesterday. “In the case of Sen. Cruz, my argument is it wasn't just the intelligence vote. I mean, he talks tough on some of these issues. For example, he was going to carpet bomb ISIS. But the only budget he's ever voted for in his time in the Senate is a budget that cut defense spending by more than Barack Obama proposes we cut it. He voted against the Defense Authorization Act every year that it came up. And that is the bill and I assume that if he voted against it, he would veto it as president. That's the bill that funds our troops. Even the Iron Dome for Israel. So I guess my point is each time he's had to choose between strong national defense and some of the isolationist tendencies in American politics, he seems to side with the isolationist. And this is an important issue to have a debate over. It's not personal.”

Clinton up nine in Iowa, per Des Moines Register/Bloomberg poll

Turning to the Democratic presidential race, a new Des Moines Register/Bloomberg poll out this morning shows Hillary Clinton leading Bernie Sanders by nine points, 48%-39%. And nationally, our NBC/WSJ poll has her ahead by 19 points, 56%-37% -- though that’s down from her 31-point lead back in late October, 62%-31%.

On the trail

Hillary Clinton attends the National Immigration Integration conference in Brooklyn, NY at 2:30 pm ET… Donald Trump holds a rally in Las Vegas at 10:30 pm ET… Marco Rubio also rallies in Vegas at 5:00 pm ET… Rand Paul hits Arizona… Mike Huckabee is in Nevada ahead of tomorrow’s debate… And Bernie Sanders stumps in New Hampshire.

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