Trump was caught off guard by voter questions at the ABC News town hall, which could spell trouble for the presidential debates

Asked how he's getting ready for the Sept. 29 debate against Joe Biden, Trump said, "I sort of prepare every day by just doing what I'm doing."

• After President Donald Trump was unable to answer basic questions from undecided voters at an ABC town hall event Wednesday night, his debate prep strategy — or lack thereof — became apparent.
• Asked on "Fox & Friends" how he's getting ready for the first presidential debate against Democratic nominee Joe Biden on Sept. 29, Trump said, "I sort of prepare every day, by just doing what I'm doing."
• Setting Trump's penchant for winging it aside, first-term presidents have historically seen a modest incumbency disadvantage going into debates against challengers who got plenty of practice during the primaries.
• The Obama-Romney opening debate in 2012, along with Carter vs. Reagan in 1980 and even the first Bush vs. Gore debate in 2000 demonstrate how the insulary effects of incumbency can spell trouble.
• Despite the president's holding pattern of being cocooned in fawning praise, Tuesday night should serve as a wakeup call as Biden heads into the debate with both more practice and lower expectations thanks to the Trump campaign's own "cognitive decline" attacks.
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Asked recently how he's preparing for the upcoming debates against Democratic nominee Joe Biden, President Donald Trump gave an answer reminiscent of a high-schooler caught off guard about an exam.

"I sort of prepare every day by just doing what I'm doing," Trump said on "Fox & Friends" on Tuesday. 

Trump's performance at an ABC News town hall event later that night highlighted the "sort of" in that quote — especially with the first presidential debate being less than two weeks away on Sept. 29.

The president was unable to answer basic questions from undecided voters for large stretches of the evening.

At one point, a voter asked Trump a straightforward question on what he would do about unemployment stemming from the coronavirus pandemic. The president quickly veered off on a series of tangents, jumping around from sanctuary cities to China and then back to "Democrat-run cities" before the ABC News anchor George Stephanopoulos had to cut to commercial.

The event featured other equally bizarre moments, like when Trump said that "a lot of people think the masks are not good."

"Who are those people?" Stephanopoulos asked.

"Waiters," Trump replied.

—ABC News (@ABC) September 16, 2020

Putting Trump's penchant for winging it aside, first-term presidents have historically seen a modest incumbency disadvantage going into debates against challengers who got plenty of practice during the primaries.

In 2012, Barack Obama was widely considered to have been "trounced" and caught flat-footed by Sen. Mitt Romney in their first debate, with polls showing solid margins in favor of the Republican challenger's performance. 

In 1980, Ronald Reagan trailed incumbent Jimmy Carter by three points going into their one and only debate. Carter's attacks on Reagan didn't stick, and the Gipper went on to beat the sitting president by 10 points on Election Day.

The isolating effects of incumbency are not limited to the president.

In 2000, then-Vice President Al Gore was expected by many to school George W. Bush in their first debate, wielding his sharp policy knowledge to fillet the more plainspoken Texan on live TV. 

The Bush campaign began prepping in April, while Gore's team remained confident in his intellectual acuity. A series of sighs from Gore and his repeated use of the term "lockbox" wound up becoming the big takeaway from the night as Bush exceeded expectations, going on to win the race.

Biden has reportedly been doing debate prep since before the conventions, and he's not only had practice during the primaries, but also key high-stakes, one-on-one debates against Sarah Palin and Paul Ryan when he was Obama's running mate.

On the expectations front, the Trump campaign's efforts to paint Biden as senile have already backfired with the former vice president's convention speech, yet the president and his surrogates keep doubling down.

Trump even repeated his 2016 line on how Hillary Clinton was juicing with performance-enhancing drugs, telling "Fox & Friends" that Biden must be "taking something, or taking something that gives him some clarity … Maybe he had 15 cups of coffee."

Whether the debates really matter remains an open question, particularly after 2016. 

However, with Trump still down six to seven points behind Biden in national polling averages, the debates may matter a lot more for him now than they did four years ago.

If Wednesday night gave undecided voters any takeaways, it proved how "sort of" preparing for the debates in cruise control may not be enough for Trump to catch up to Biden in time for Nov. 3.