WEST PALM BEACH, Florida - Donald Trump used his 78th birthday party on Friday to promise deeper tax cuts if he wins the Nov. 5 U.S. election and to make vague predictions of future attacks on U.S. soil after the arrest of Tajik nationals with suspected ISIS ties.

Speaking to thousands of supporters at a convention center in West Palm Beach, Florida, the Republican candidate vowed to further cut the corporate tax rate he lowered while president, while also providing tax relief to the middle class.

Trump, who is locked in a close rematch race with President Joe Biden, a Democrat, did not provide specifics. Trump slashed the corporate tax rate to 21% from 35% and implemented several other tax breaks that are due to expire next year.

"I want to make them permanent, and then I'm going to reduce taxes by still more," Trump said, without offering a plan to offset the possible decline in revenue. "I want to get it down still further, and especially for the middle income people."

Trump, who made a hardline stance on immigration a centerpiece of his administration and has vowed a wide-ranging crackdown if reelected, again lambasted Biden's efforts to curb the flow of migrants crossing into the U.S. illegally.

Trump highlighted the recent arrests of eight people from Tajikistan in New York, Los Angeles and Philadelphia who, according to a person familiar with the investigation, had suspected links to the extremist group ISIS.

U.S. Immigration and Customs Enforcement said the people had been arrested in coordination with the FBI’s Joint Terrorism Task Forces and were being held on immigration charges, though the agency did not confirm the possible ISIS link.

"Our country has never been in danger like it is in danger right now," Trump said, claiming without evidence that thousands of terrorists were pouring into the United States. "Our country is going to pay a steep price for many, many years."

Biden has toughened his approach to immigration as it emerged as a major political vulnerability for him. Earlier this month he instituted a broad asylum ban on migrants caught illegally crossing the U.S.-Mexico border.

Republicans in Congress earlier this year rejected a bipartisan effort to toughen immigration rules after Trump told them not to pass it and give Biden a political win.

 

COGNITIVE TEST

Standing next to a towering cake topped with a "MAGA" hat, marking his "Make America Great Again" slogan, Trump spoke to a raucous crowd of supporters, many wearing red, white and blue. The event was organized by a group of supporters called Club 47 USA, whose name is a nod to their hopes that he becomes the 47th president.

Age and mental sharpness have been at the center of the contest between the Trump and Biden, often getting more attention than substantive policy issues.

Public opinion polls show Americans are more worried about the advanced age of Biden, who is 81. But at 78, Trump is just three-and-a-half years younger and he would be the oldest person ever to be inaugurated if he wins a second term.

While not explicitly taking issue with Biden's age, Trump once again sought to portray his Democratic rival, who sometimes makes verbal mistakes and has a slowing gait, as physically frail and mentally unfit to occupy the Oval Office.

Calling Biden and his administration "grossly incompetent" and "probably the dumbest leadership in the world," Trump said that "all presidents should have aptitude tests," before referring to a cognitive test he said he took during his term.

Biden has responded to questions about his age by telling voters to focus on his accomplishments in office as evidence of his acuity and strength. He has described Trump as a threat to democracy following his efforts to overturn the 2020 election and criticized his sometimes rambling speeches, as well as his use of inflammatory rhetoric against immigrants.

"Happy 78th birthday, Donald. Take it from one old guy to another: Age is just a number," Biden posted to social media platform X along with a video contrasting his actions with those of Trump. "This election, however, is a choice."

In a Reuters/Ipsos poll in February, some 78% of respondents - including 71% of Democrats - said Biden, already the oldest president, was too old to work in government. Some 53% of respondents said Trump, who was president from 2017-2021, was too old for government work.

It is unclear to what extent age will be a factor in the final outcome. Among issues that voters will be weighing is the strength of the economy, which overall is performing well but is beset by inflation, as well as immigration and abortion rights.

The first televised debate on June 27 will be an important test for both Biden and Trump, with voters looking for verbal slip-ups as a possible indicator that they might not be up to the task of leading the country.

(Reporting by Nathan Layne in Wilton, Connecticut, and Jeff Mason and Ted Hesson in Washington; Editing by Colleen Jenkins, Leslie Adler, Rod Nickel and William Mallard)