PHILADELPHIA, March 9, 2024 (BSS/AFP) - US President Joe Biden stepped up his attacks on Donald Trump Friday as he took his election message to crucial battleground states on the back of a combative, well-received State of the Union address.

Speaking to supporters in the swing state of Pennsylvania, 81-year-old Biden finally attacked Trump by name, a day after he had referred to him only as "my predecessor" multiple times.

"Donald Trump and the MAGA Republicans are trying to take away our freedoms, and that's not an exaggeration," Biden said, referring to Trump's "Make America Great Again" slogan.

"Well guess what? We will not let him."

The Democrat slammed Trump for backing abortion bans and for inviting Russian President Vladimir Putin to invade NATO members that don't pay their bills.

He also criticized Trump for meeting Friday with Hungarian Prime Minister Viktor Orban, who he said "is looking for dictatorship." Orban has also angered EU allies by maintaining ties with Putin after the invasion of Ukraine.

Biden's wife Jill Biden gave a lively introduction at the campaign event in Philadelphia in which she also laid into Trump.

"Donald Trump is dangerous to women and to families and to our country and we can't let him win" in November's election, she said.

A smiling First Lady also hailed her husband's performance in the set-piece State of the Union speech, saying: "Did you all see Joe last night? Wasn't he on fire?"

Dozens of demonstrators however rallied outside the venue to protest against Biden's support for Israel's offensive in Gaza after the Hamas attacks on October 7.

- 'Grand slam ' -

Pennsylvania is Biden's first stop of a tour of all the key battleground states in March as the race to stop a White House comeback by Trump starts in earnest.

Biden travels on Saturday to Atlanta, Georgia -- the same state where Trump is giving a rally on the same day.

He then heads to New Hampshire on Monday, Wisconsin on Wednesday and Michigan on Thursday.

Along the way, the president will look to ride a wave of momentum from the State of the Union speech, which ratings firm Nielsen estimated was seen by 32 million people, up from last year's viewership of 27 million.

A pumped-up Biden on Thursday launched one of the most scorching addresses ever seen from the podium of the House of Representatives, transforming what used to be a somber set-piece occasion into a raucous political rally.

He repeatedly attacked Trump for "bowing down" to Putin and being a threat to US democracy, while assailing Republican lawmakers in the chamber as the former president's stooges.

The aim was also to ease concerns of skeptical voters about his age, with America's oldest president bringing the fight in an energetic performance that saw him spar with Republicans in exchanges sprinkled with jokes.

"President Biden hit a grand slam," White House Press Secretary Karine Jean-Pierre told reporters flying with him to Philadelphia.

Trump, 77, hit back at Biden on Friday, saying Biden was a "psycho" and saying his speech was "getting 'panned' all over the world," without offering any examples.

Trump has said that he will debate Biden on television "anytime" but Biden told reporters on Friday that it "depends on his behavior."

Biden has branded Trump a threat to democracy. The former president faces multiple criminal cases, including for trying to overturn his 2020 election loss to Biden, and a $355 million civil fraud fine.

But he currently holds a narrow lead over Biden in the polls.