Recent polling in a slew of states that carried President Trump to his thin win in 2016 show him starting 2020 in a deep hole.

What's new: Based on demographic changes, Republicans for the first time have authentic worries about Arizona, Georgia, Texas and other states they once took for granted.

Why it matters: Trump's margin for error this time is much smaller, because he's being squeezed from the north and the south.

From the north : Michigan, Wisconsin and Pennsylvania are harder this time because Hillary Clinton, a turnoff for many working-class voters, won't be on the ballot.

: Michigan, Wisconsin and Pennsylvania are harder this time because Hillary Clinton, a turnoff for many working-class voters, won't be on the ballot. From the south: Demographics are making North Carolina, Georgia, Texas and Arizona more competitive, and realistically in play.

Demographics are making North Carolina, Georgia, Texas and Arizona more competitive, and realistically in play. That's part of the reason for the fascination with more centrist Democrats like Sen. Amy Klobuchar, Beto O'Rourke and Joe Biden: The states that Trump won, but could easily lose, are swingy — not super-liberal.

Among the holes in his 2016 map:

In Wisconsin, the Milwaukee Journal Sentinel wrote after a statewide poll in January that Trump "has a precarious path to victory," based on the facts that his job approval was just 44%, opposition was more intense than support, and Democrats were more unified than Republicans.

the Milwaukee Journal Sentinel wrote after a statewide poll in January that Trump "has a precarious path to victory," based on the facts that his job approval was just 44%, opposition was more intense than support, and Democrats were more unified than Republicans. In Michigan , the Detroit Free Press reports that Trump faces "serious headwinds": "Less than half of likely voters believe he’s doing a good job, according to some recent polls, and many, if not most, plan to vote for someone else."

, the Detroit Free Press reports that Trump faces "serious headwinds": "Less than half of likely voters believe he’s doing a good job, according to some recent polls, and many, if not most, plan to vote for someone else." "Pennsylvania meltdown triggers Republican alarms," Politico wrote after the midterms. "A GOP collapse threatens to torpedo Donald Trump’s re-election prospects."

triggers Republican alarms," Politico wrote after the midterms. "A GOP collapse threatens to torpedo Donald Trump’s re-election prospects." In last weekend's Iowa Poll, 67% of Republicans said they would definitely vote to re-elect Trump, while 27% said they would consider someone else or definitely vote for someone else. 40% want a GOP challenger.

But Trump allies tell me their 2016 upsets reduce their current worry:

"He’s basically where he was and, depending on the poll, possibly better than where he was going into the 2016 general election," a current adviser said. "I wouldn’t say this is a bad place to be."

where he was and, depending on the poll, possibly better than where he was going into the 2016 general election," a current adviser said. "I wouldn’t say this is a bad place to be." "Democrats will go through exactly what Republicans did in 2016," added an alumnus of Trump's campaign and White House. "The question is where they can coalesce around a single candidate — not sure that’s possible with all the differing factions."

Be smart: "I’d sooner be the Dems than Trump," David Axelrod, Obama's campaign architect, told me. "He drew an inside straight in 2016 with narrow wins in Wisconsin, Michigan and Pennsylvania. He is vulnerable today in each, with no obvious prospect of adding a state to his column in 2020."