"Apparently he had my speech on Air Force One," Biden said around the same time, 250 miles away in Mount Pleasant, Iowa. "I guess he is really fascinated with me I find it fascinating."
It was a political version of the putdown favored by passive-aggressive teenagers everywhere – why are you so obsessed with me? –
In the end, it was Biden who singled out Trump more often by name – 35 times, according to CNN's count – compared to 15 mentions of Biden by the President.
Still, for both men ̵
Trump has singled out Biden as the most formidable threat to the blue -collar voters who propelled him to the White House in 2016 – and polls (both public and internal) have shown Trump lagging behind the former vice president in states that were central to his victory.
That's on top of Trump's lingering fixation with his predecessor, President Barack Obama, and the link to that administration Biden represents.
Biden, meanwhile, has framed his entire campaign on the grave necessity of defeating the President. Unlike some of his Democratic rivals – who were left on the sidelines Tuesday as the center-ring candidates sparred – Biden has decided to focus squarely on Trump, even as he talks sanguinely of not being drawn into aa mudslinging match.
A preoccupation with the incumbent has lent his campaign a general election sensibility, all in keeping with the image of a front-runner he's eager to maintain.
Blow for blow
With those motivations in mind, each tore into the other on Tuesday. On their first day trading attacks in an early voting state, a picture emerged of a potential general election match-up colored by personal insults, open hostility – and attacks striking in their similarity.
Over the course of three events in the eastern part of the state, Biden deemed the President an "existential threat" to the country, questioning his intelligence on matters of policy and casting him as clueless to the struggles of working Americans.
"I do not think the President really gets the basics, "Biden said during an evening speech in Davenport, which was so heavy on Trump insults that his campaign sought to program the whole day around it, releasing prepared text of the whole thing at 6 o'clock in the morning.  Lampooning Trump's onetime declaration that "I alone can fix" the country's problems, Biden scoffed: "Fix yourself first, Donald Trump."
He decided to give a line from the prepared text declaring cashiers at Target "know more about economics than Trump."
The President, too, went after Biden's smarts, albeit in far cruder terms.
"Joe Biden is a dummy, "he declared on the White House South Lawn before departing for Iowa, adding later:" He looks different than he used to, he acts different than he used to, he's even slower than he used to be. do not know. "
Trump, of course, is no stranger to allegations of mental decline; he was so eager to disprove claims of senility that he asked his doctor to administer a mental acuity test and release the results publicly in 2017. Like many of Trump's insults, the accusation did not come with many specifics.