Newsletter: Essential Politics: The most unpopular nominee ever?

“I beat Hillary in many of the polls that have been taken. And each week, I get better and better.”

Some of Donald Trump’s statements can be hard to evaluate. That one’s easy. Since the start of February, 19 polls have been taken by a wide range of survey organizations testing a potential matchup between Trump and Hillary Clinton; she led in 18 of them. Her margin over Trump has steadily widened and, on average, now stands at about 10 points.

Good afternoon, I’m David Lauter, Washington Bureau chief. Welcome to the Friday edition of our Essential Politics newsletter, in which we look at the events of the week in the presidential campaign and highlight some particularly insightful stories.

As he has mowed down one Republican challenger after another, Trump has taken on the image of an indestructible candidate who can brush aside any attack without suffering damage.

Not so.

Yes, the attacks on Trump have done little, if anything, to shake the support of his ardent backers, who consistently yield 35% to 45% of the votes in the Republican primaries. But as I noted in an article earlier this week, the impact on the wider electorate has been very different.

Only about 25% of Americans now have a positive view of Trump, and the Democratic campaign against him hasn’t really started yet. Trump has proved to be a skilled politician, but he would start a general-election campaign in a deep hole. If he becomes the GOP candidate, he may well be the most unpopular major-party nominee ever.

First, of course, Trump needs to nail down the 1,237 delegates needed to claim the nomination when the Republicans hold their convention in July in Cleveland.

Tuesday’s primaries will go a long way toward deciding if that happens or if the Republicans land in Cleveland with their nomination still up for grabs. As Mark Z. Barabak explained, the key race to watch is Ohio, where Gov. John Kasich continues to run close to Trump in polls.

By contrast, Florida’s Sen. Marco Rubio has run far behind Trump in polls of his state, which also votes Tuesday. Rubio has come under pressure to drop out, but as Lisa Mascaro reported, he has vowed to press on at least until the Florida result.

Mascaro also took an insightful look into Rubio’s suburban strategy and why it has fallen so badly short.

Texas Sen. Ted Cruz has focused on the contests in North Carolina, Missouri and Illinois, which award delegates proportionately. Ohio and Florida have outsized impact because they are the night’s two winner-take-all contests on the GOP side.

You can follow the outcome of all the primaries, as we post live results, speeches and analysis on Trail Guide.

And as the race unfolds, keep watch on the delegates in both parties with our Delegate Tracker, which shows where each candidate stands and where they have won support.

On the Democratic side, the party has a more straightforward choice, as Cathy Decker explained in her analysis after Wednesday night’s Democratic debate: Clinton’s known negatives versus Sen. Bernie Sanders’ suspected ones.

Currently, Sanders does well in hypothetical matchups against Trump and other Republicans. But Democrats got a reminder in Wednesday’s debate of how little vetting the Vermont senator has gone through -- a video clip of a long-ago interview in which he had kind words for Fidel Castro.

Meanwhile, although Sanders upset Clinton in Michigan this week and may beat her in at least some of the contests this coming Tuesday, she continues to expand her lead over him in the delegate count.

Looking ahead at the general election, Kate Linthicum examined the migration of Puerto Ricans to Florida, which is changing the political balance of the nation’s biggest swing state.

And before we forget the campaign we’ve been through, Seema Mehta had this profile of Mike Murphy, the much-heralded Republican strategist who burned through $100 million in a fruitless effort to win the nomination for Jeb Bush.

Finally, one major issue that Democrats hope will play to their advantage this fall, both in the presidential race and in Senate contests, is the fight over the Supreme Court. Read Michael A. Memoli‘s report on the politics of the nomination.

And if you’d prefer to get your campaign insight via podcast, check out our latest on Trump and the media.

What we’re reading

Few reporters have written more insightfully about President Obama and his foreign policy than the Atlantic magazine’s Jeffrey Goldberg. His latest piece on the “Obama Doctrine,” based on several interviews with the president, is a must-read.

That wraps up this week. My colleague Christina Bellantoni will be back Monday with the weekday edition of Essential Politics. Until then, keep track of all the developments in the 2016 campaign with our Trail Guide, at our politics page and on Twitter at @latimespolitics.

Send your comments, suggestions and news tips to politics@latimes.com.