“For the first time in history, a former president has been indicted, and we can’t find a marker in this survey that it’s had an impact with his standing,” said Republican pollster Bill McInturff of Public Opinion Strategies, who conducted this survey with Democratic pollster Jeff Horwitt of Hart Research Associates.

“Not only are they sticking with Trump post-federal indictment,” Horwitt said of Republican voters, “there are several signs that his support is growing or others are losing ground, particularly Ron DeSantis.”

The trouble for Trump comes not among Republicans but among the general electorate: A majority of all registered voters have concerns about Trump after his indictment on federal criminal charges, including 55% of independent voters. And President Joe Biden leads Trump by 4 points in the NBC News poll’s first hypothetical general-election matchup for 2024.

But the survey shows that majorities of all registered voters have concerns about both Trump’s and Biden’s mental and physical health, as well as reservations about either serving another four years as president.

The NBC News poll was conducted June 16-20 — beginning a week after a federal grand jury indicted Trump on criminal charges for mishandling classified documents that were discovered last year at his Mar-a-Lago residence.

Yet the poll shows Trump with a sizable — and growing — lead over his Republican presidential rivals in the aftermath of that federal indictment.

Fifty-one percent of national Republican primary voters pick the former president as their first choice in the race for the 2024 GOP presidential nomination, followed by 22% who choose DeSantis, 7% who select former Vice President Mike Pence and 5% who want former New Jersey Gov. Chris Christie.

No other Republican candidate gets more than 4% support.

Trump’s 29-point lead over DeSantis in a multi-candidate field is an increase from April’s NBC News poll, when 46% preferred Trump as their first choice versus 31% who picked DeSantis. That survey was conducted soon after the former president was indicted in New York for his alleged role in a hush-money case.

When the GOP presidential race gets reduced to just two candidates in the current survey, Trump gets support from 60% of Republican primary voters, while DeSantis gets 36%.

A combined 77% of GOP primary voters say the federal charges against Trump in the classified document case give them either minor concerns (14%) or no real concerns at all (63%).

That’s compared with 55% of all registered voters who say the charges give them either major concerns (47%) or moderate concerns (8%).

And 64% of Republican primary voters believe that the multiple indictments and investigations Trump faces are politically motivated, and they say they must support him to stop his opponents from winning — although that’s down slightly from the 68% who said this in April after his first indictment in the New York case.

Half of Republicans want Trump to continue as party leader

The NBC News poll also finds nearly half of Republican primary voters — 49% — say that Trump should continue as the party’s leader. These voters overwhelmingly pick Trump as their first choice on a primary ballot.

Another 21% say it’s time to consider other leaders, even though they believe Trump was a good president. A majority of these voters pick DeSantis as their first choice, yet Trump also gets support from 1 out of 5 in this group.

And 29% say the GOP needs a new leader with better personal behavior and an approach different from Trump’s. This group’s support is spread among DeSantis, Pence, Christie and other candidates.

While a combined 50% of GOP primary voters are open to a leader besides Trump, Republican pollster McInturff says that Trump’s 49% “is a strong starting number” in a field with multiple candidates.

“Something has to happen to shift this race,” he said, adding that the early nominating contests of Iowa and New Hampshire have shown the potential to do that in past presidential campaigns.

Measuring a Biden versus Trump rematch

For the first time in the 2024 presidential cycle, the NBC News poll tests a hypothetical general-election matchup between Trump and President Biden.