Richmond, Virginia - Barack Obama is still very much on Donald Trump's mind as the frontrunner for the Republican presidential nomination yet again got confused during a campaign rally in Virginia.

As questions about the mental acuity of both presumptive presidential nominees continue to grow, it was Trump's turn to add grist to the mill with a significant slip on Saturday.

Speaking to supporters in Richmond, the 77-year-old turned to the issue of Russian aggression, but seemed to confuse President Joe Biden for the previous Democratic office holder, Obama.

"Putin has so little respect for Obama that he's starting to throw around the nuclear word. You heard that! Nuclear. He's starting to talk nuclear weapons today," Trump said, as the crowd grew silent.

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"We have a fool – a fool as a president," he continued, clearly meaning Biden, before moving on to insist that he would get the Ukraine war "settled."

It's not the first time Trump has gotten mixed up recently. Aside from mistakenly mentioning Obama twice before, he also confused his Republican rival Nikki Haley for former House Speaker Nancy Pelosi.

Biden has also faced increased scrutiny for frequent gaffes, the latest of which came on Friday, when he repeatedly said "Ukraine" while announcing air drops of aid for Gaza.

Polling shows a majority of all registered voters think Biden, who will turn 82 this year, is too old to be an effective president. Only 42% feel the same way about Trump.