WASHINGTON  –  Donald Trump limbered up for his debate with Kamala Harris by showing the extremism that risks playing into the vice president’s claim that he’s an “unserious man” who is an “extremely serious” threat if he’s returned to the White House.

Trump warned he will jail election officials he considers cheats; is complaining Pennsylvania’s voting is a fraud; vowed to pardon January 6 rioters; railed against women who accused him of sexual misconduct; and spent hours in recent days on sometimes incoherent rants that raised questions about his state of mind.

But new polling ahead of Tuesday’s showdown in Philadelphia shows the race tied up nationally, suggesting Harris’ momentum after replacing President Joe Biden on the ticket hasn’t resulted in a commanding edge.

The tightness of the contest shows both Trump’s enduring appeal to tens of millions of Americans as he seeks a political comeback and the huge task facing Harris as she tries to save an election Democrats seemed doomed to lose before Biden bowed out.

That makes Tuesday’s debate — the first since June’s consequential clash on CNN that eventually ended Biden’s campaign — the most critical scheduled event before Election Day.

The way each candidate is preparing highlights the different paths Americans can choose in November and the sharp contrast in the style of the presidency that will ensue if Harris or Trump are at the Oval Office desk.

Harris is holed up in Pittsburgh with staff to hone her skills for the test of facing Trump in a debate. Her choice of Pennsylvania for prep stresses the critical importance of a state she almost certainly needs to win to take the presidency. A source told CNN that her advisers are working out how she’ll deal with a rule that a candidate’s mic will be muted while their rival speaks. The vice president had pushed to overturn the restriction in the hope she could use her skills as a former prosecutor to dress down Trump in real time. But she told reporters, “I’m ready,” as she went for a stroll in the Steel City on Sunday with her husband, second gentleman Doug Emhoff.

Transportation Secretary Pete Buttigieg reflected on Harris’ challenge as she tries to engage Americans who want to know more about her while dealing with a sometimes-unhinged force of nature like Trump. “It will take almost superhuman focus and discipline to deal with Donald Trump in a debate,” Buttigieg said on CNN’s State of the Union. “It’s no ordinary proposition, not because Donald Trump is a master of explaining policy ideas and how they’re going to make people better off. It’s because he’s a master of taking any form or format that is on television and turning it into a show that is all about him.”

A New York Times/Siena College poll published Sunday showed that 28% of likely voters need to know more about Harris, as opposed to just 9% who say the same of her rival. This presents possible room for growth for the vice president. But she is also facing pressure to explain policy reversals on issues such as immigration and fracking while showing more precision than she did in some testy interviews early in her vice presidency. And her unwillingness to submit to major media interviews — apart from one last month on CNN — means that a candidate who has sometimes struggled to articulate coherent arguments in high-pressure and spontaneous situations is coming into the debate without much recent experience of adversarial political combat.

Trump’s Republican supporters have been pleading with him for days to drill down on issues such as the economy, immigration and national security and to avoid petulant behavior that could play into Harris’ argument that it’s time for the country to move on from the bitterness and chaos he represents for many voters. The GOP theory is that Harris, as a key member of an unpopular administration, is ill suited to act as an agent of political change.

But Trump’s conduct heading into the debate explains the concern he will botch the clear contrast spelled out by Sen. Tom Cotton to CNN’s Dana Bash on “State of the Union.” The Arkansas Republican said: “People remember that, when Donald Trump was in office, prices were low, wages were high, we had peace and stability around the world.” He added: “Kamala Harris, as vice president, has brought us record high inflation. We have a wide-open southern border and we have war everywhere you turn around in the world.”

Trump, however, was unwilling to restrain himself in recent days. (CNN)…[+]