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.

Is Trump on the Verge of his Biggest Victory Yet?

Three days to go until Saturday’s Republican primary in South Carolina, and all of the polling out there suggests that Donald Trump is in clear command of the race. The latest poll via CNN: Trump 38%, Ted Cruz 22%, Marco Rubio 14%, Jeb Bush 10%. And if Trump pulls it off -- remember, the polling was right in New Hampshire, but off in Iowa -- it would be his biggest victory yet.

For starters, South Carolina isn’t New Hampshire: 65% of Republican voters in the Palmetto State are evangelical Christians, per the 2012 exit polls, versus the 25% we saw in New Hampshire. Also, while only 55% of GOP voters in the Granite State considered themselves to be Republicans (due to the state’s heavy presence of independent voters), it was 71% in South Carolina four years ago.

Yet beyond demographics, South Carolina has been Bush Country in past cycles -- George HW Bush won it in 1988 and 1992, George W. Bush won it in 2000, and John McCain won it in 2008. Yes, New Gingrich was your 2012 victor, breaking the state’s streak in its winner going on to be the GOP’s presidential nominee. But if Trump wins South Carolina on Saturday, it not only would give him a clear path to the nomination; it also would be another sign how much the Republican Party has changed since 2008.

Town Halls Galore!

Speaking of Trump and South Carolina, he will participate tonight there in a town hall hosted by MSNBC’s Joe Scarborough and Mika Brzezinski that will air at 8:00 pm ET, while John Kasich participates in a town hall with MSNBC’s Chris Matthews at 7:00 pm ET. And, of course, tomorrow night brings us the MSNBC/Telemundo town hall in Las Vegas featuring Hillary Clinton and Bernie Sanders.

Obama Hints that he Might Endorse in the Clinton-Sanders Race

Much was made of President Obama criticizing Donald Trump during his news conference yesterday -- and deservedly so. But don’t miss this other news: It looks like Obama suggested that he might endorse someone in the Clinton-vs.-Sanders Democratic contest, though it’s unclear when that would take place.

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“I think what you're seeing among Democrats right now is a difference in tactics, trying to figure out how do you actually get things done; how do you actually operate in a political environment that's become so polarized; how do you deal with the power of special interests,” Obama said. “It's a healthy debate. Ultimately, I will probably have an opinion on it, based on both being a candidate of hope and change and a president who’s got some nicks and cuts and bruises from getting stuff done over the last seven years. But for now, I think it's important for Democratic voters to express themselves and for the candidates to be run through the paces.” (Emphasis is ours.)

Update on the Recent Polls

In addition to that CNN poll on the Republican race in South Carolina, here are some other polls we’ve seen in the last 24 hours:

South Carolina Dem race via CNN: Clinton 56%, Sanders 38%

Nevada Dem race via CNN: Clinton 48%, Sanders 47%

Nevada GOP race via CNN: Trump 45%, Rubio 19%, Cruz 17%

National Dem race via Quinnipiac: Clinton 44%, Sanders 42%

National GOP race via Quinnipiac: Trump 39% Rubio 19% Cruz 18%

Update on the Ad Spending

More than $262 million has been spent on ads in the 2016 presidential race, and the biggest advertiser has been Team Bush at nearly $81 million, according to ad-spending tracker SMG Delta. That’s followed by Team Rubio at $50 million-plus. Below are the numbers:

The biggest overall ad spenders

Team Bush: $80.9 million

Team Rubio: $50.4 million

Team Sanders: $25 million

Team Clinton: $20 million

Team Cruz: $16.8 million

Team Trump: $8.5 million

The biggest South Carolina ad spenders

Team Bush: $12.8 million

Team Rubio: $11.1 million

Team Cruz: $8.1 million

Team Trump: $1.3 million

Team Sanders: $878,000

Team Clinton: $712,000

Team Carson: $696,000

The biggest Nevada ad spenders

Team Clinton: $3.3 million

Team Sanders: $3.2 million

Team Rubio: $560,000

SOURCE: SMG Delta/NBC News

Countdown to MSNBC/Telemundo Clinton-Sanders townhall in Nevada: 1 day

Countdown to Dem Nevada caucuses: 3 days

Countdown to GOP South Carolina primary: 3 days

Countdown to GOP Nevada caucuses: 6 days

Countdown to Dem South Carolina primary: 10 days