The Note: The Debate, In Case You Missed It

— -- NOTABLES

--5 MOMENTS THAT MATTERED IN FLINT: Hillary Clinton and Bernie Sanders went head-to-head on a debate stage here Sunday night against the backdrop of the water crisis afflicting the city. But the debate, hosted by CNN, took place at a critical moment in the Democratic primary season when both candidates are in the midst of a state-by-state fight for delegates. And there was no shortage of tense moments between the two contenders. However, both candidates positioned themselves -- and their debate -- as stark contrast to the Republican field. “Compare the substance of this debate with what you saw on the Republican stage last week,” Clinton said. Sanders backed her up: “We are, if elected president, going to invest a lot of money into mental health, and if you watch these Republican debates, you know why.” Here are 5 moments that mattered at Sunday night’s debate, courtesy of ABC’s LIZ KREUTZ and MARYALICE PARKS: http://abcn.ws/1ROqCOC

--BEST LINES OF THE DEBATE: ABC’s JEFF NAFT highlights some of the best lines: http://abcn.ws/1p9EcTH THE DEBATE IN A MINUTE, from ABC’s EVAN SIMON: http://abcn.ws/1YmufOC

--WHAT WOULD IT TAKE FOR SANDERS TO WIN THE NOMINATION? Just how far ahead is Hillary Clinton? Here’s one way of looking at it, according to ABC’s RYAN STRUYK: Even if Sanders won every single remaining uncommitted superdelegate and the same number of superdelegates who left Clinton for Obama in 2008 also defected to Sanders this year (57), Sanders would need to win every single remaining state and territory by 10 percentage points in order to win the nomination.

--ANALYSIS -- ABC’s RICK KLEIN: What if the establishment lane was never open for business in the first place? What if the problem wasn’t traffic problems, or a Bush in the road, or that fancy boots got stuck in sticky pavement? With Chris Christie and Jeb Bush gone, and Marco Rubio and John Kasich left scrambling to win their home states, Republicans are facing the prospect of seeing Ted Cruz emerge as their main alternative to Donald Trump. That may be a prospect less likely than Trump as frontrunner: Cruz could wind up being the establishment’s actual choice in a winnowed field. Trump can be beaten – his most recent showings suggest new and continuing vulnerabilities – though not by just anybody, it would appear. By all appearances, Rubio has only gotten weaker from attempts by the party’s elected leaders and money folks to rally behind him. Cruz needs to be careful what he wishes for, on a couple levels. Asked about a contested convention, Cruz said on CBS that powerbrokers choosing a nominee at a convention would be “illegitimate” and “wrong.” We’ll see how he feels as we get closer to Cleveland. BONUS ANALYSIS: Democratic Debate Takes Fiery Turn, But Stays on Substance http://abcn.ws/1RvS80J

YESTERDAY ON THE TRAIL with ABC’s VERONICA STRACQUALURSI and PAOLA CHAVEZ

BERNIE SANDERS WINS MAINE DEMOCRATIC CAUCUSES. Democratic presidential candidate Bernie Sanders won the Maine Democratic caucuses, according to the Associated Press. Maine Democrats held 533 caucuses at approximately 400 locations across the state, and 30 delegates are at stake. On Saturday, Sanders won the Kansas and Nebraska caucuses while rival Hillary Clinton took the Louisiana primary, ABC’s MICHAEL FALCONE notes. http://abcn.ws/1p0UjCu

RUBIO WINS PUERTO RICO GOP PRIMARY. Florida Sen. Marco Rubio was the winner of the Puerto Rico primary, the Associated Press said, after voters in the U.S. territory cast their ballots yesterday for the 2016 Republican presidential nomination. With 100 percent of precincts reporting on the island, Rubio garnered 73.8 percent of the vote, Trump 13.6 percent, Cruz 9 percent and Kasich 1.4 percent. Sunday's Puerto Rico primary marks the first time in all of the GOP contests this cycle a candidate has won a majority of the vote. Rubio won all 23 delegates. Rubio, who campaigned in Puerto Rico Saturday, has now won one state and one territory, ABC’s EMILY SHAPIRO reports. http://abcn.ws/1SsxUtC

ARNOLD SCHWARZENEGGER ENDORSES JOHN KASICH, CALLS HIM ‘ACTION HERO.’ Arnold Schwarzenegger, the movie star and former California governor, endorsed Ohio Gov. John Kasich Sunday for the Republican nomination for president, saying his experience in government made him "an action hero." "He kicked some serious butt," Schwarzenegger said of Kasich, who served in Congress for 18 years. "He was an action hero when he went to Washington." Schwarzenegger, a fellow Republican, told hundreds at a botanical garden and conservatory that he first became friends with Kasich in the 1980s, when he was in Ohio hosting his annual "Arnold Sports Festival" body-building and fitness expo, ABC’s BEN GITTLESON notes. http://abcn.ws/1U57oX9

NOTED: KASICH PREDICTS BETTER PRIMARY PERFORMANCES ‘IN THE NORTH.’ Kasich predicted he'll perform better during Republican nominating contests in the weeks to come after he "survived" early primaries and caucuses in the southeastern United States. “The calendar worked in the south [but] didn’t work great for me,” Kasich said Sunday on ABC’s “This Week.” “We never worried about that. Our strategy was always to survive and get to the north, and now we’re getting to the north.” ABC’s BEN GITTLESON reports: http://abcn.ws/1p02VJC

RNC CHAIR DOUBTS THERE WILL BE BROKERED CONVENTION. Republican National Committee Chairman Reince Priebus highly doubts there will be a brokered convention in Cleveland this summer despite growing talk of one within his own party. “I just don’t see that happening,” he said Sunday on ABC's "This Week With George Stephanopoulos." "It doesn't mean it's impossible -- it just means that you don't know what next week is going to bring, or the week after, or a month from now. “ Priebus emphasized the party will be “100 percent for the nominee” despite calls from the last GOP presidential nominee, Massachusetts Gov. Mitt Romney, to stop frontrunner Donald Trump by splitting delegates and forcing a brokered convention,  ABC’s ADRIENNE SALAZAR writes. http://abcn.ws/1U4BgTu

BERNIE SANDERS SEES ‘PATH TOWARD VICTORY’ AFTER MORE CAUCUS WINS. Vermont Sen. Bernie Sanders sees a "path toward victory" after winning the Democratic caucuses in Nebraska and Kansas. Sanders said Sunday on ABC's "This Week with George Stephanopoulos" his campaign was happy about the states he has won. He won two of the three states Saturday, losing to Hillary Clinton in Louisiana. "I think geographically, we are looking good. I think we have a path toward victory," he said. Sanders said he's looking ahead to states that vote in April and as late as June despite trailing Clinton, according to ABC’s JOSH HASKELL. "We think we have an excellent chance to do well out on the West Coast in California, state of Washington, Oregon," he said. "We think we have an excellent chance to do well in large states like New York. We think we're going to surprise people here in Michigan." http://abcn.ws/1p8Kfbp

IN CASE YOU MISSED IT

CANDIDATES REACT TO DEATH OF FORMER FIRST LADY NANCY REAGAN. The 2016 presidential candidates paid tribute to former first lady Nancy Reagan, who died in her home in Los Angeles on Sunday. Ohio Gov. John Kasich said: "President Reagan has been reunited with his wife and partner but America and the Reagan family have lost a woman of grace and strength.” Sen. Bernie Sanders said: "No matter your party or political ideology, this is a sad day for America. Nancy Reagan was an exemplary first lady." ABC’s EMILY SHAPIRO has more: http://abcn.ws/1R1AiIP

WHO’S TWEETING?

@MrWalterShapiro: Maybe I am jaded after constant GOP vulgarity, but Bernie Sanders you're no Rick Lazio or anything close.

@ZekeJMiller: Trump Tower Funded by Rich Chinese Who Invest Cash for Visas http://bloom.bg/1TCMsZe  via @bpolitics

@sbg1: How Trump scrambles the general election map: important read here from @politicosteve. http://www.politico.com/story/2016/03/trump-2016-general-election-map-220196 …

@SopanDeb: .@club4growth launches $2 million ad buy in Illinois for anti-Trump ads.

@wpjenna: Randy Kendrick, wife of Arizona Diamondbacks owner, works to mobilize conservative donors against Donald Trump: http://wpo.st/OyHJ1