Former US President and current Republican frontrunner Donald Trump has been spreading rumors and fueling talk before the big and first CNN debate about US President Joe Biden submitting to a pre-debate drug test which the Biden campaign called "desperate".

Trump wrote on Truth Social on Monday afternoon: "DRUG TEST FOR CROOKED JOE BIDEN??? I WOULD, ALSO, IMMEDIATELY AGREE TO ONE!!!" 

During his rally on Saturday in Philadelphia, Trump insisted that Biden's strong show on Thursday night was the result of him using performance-enhancing drugs.

"So, a little before debate time, he gets a shot in the ass — they want to strengthen him up so he comes out, he'll come out, okay, I say he'll come out all jacked up, right? All jacked up," Trump told the crowd, and a Biden campaign spokesperson quickly jumped to deny it.

"Donald Trump is so scared of being held accountable for his toxic agenda of attacking reproductive freedom and cutting Social Security that he and his allies are resorting to desperate, obviously false lies," the spokesman said.

Biden campaign advisor Mitch Landrieu said on CNN, "Trump's going to talk trash like that all the time because that's what he does. The other day you may remember he was trying to question our president's mental acuity and he could not remember the name of his own doctor so tell President Trump, bring whatever he's got -- President Biden will be standing there, ready for him". 

Meanwhile, Trump's team is also alleging that CNN, the host of Thursday's debate, will show preference for President Biden. Trump's national press secretary, Karoline Leavitt, fueled that claim during a CNN appearance on Monday that was cut short.

During "CNN This Morning," anchor Kasie Hunt tried to get Leavitt to answer questions regarding how Trump is preparing for the debate, but instead, Leavitt criticized CNN's debate moderator Jake Tapper. 

Hunt interrupted her twice stating that she won't allow her to publicly criticize her coworkers, after which Leavitt was removed from the program. 

After the show, Hunt took to X to say: "You come on my show, you respect my colleagues. Period. I don't care what side of the aisle you stand on, as my track record clearly shows."

In response, Leavitt also wrote on X: "You cut off my microphone for bringing up the debate moderator's history of anti-Trump lies," adding, "This proved our point that President Trump will not be treated fairly on Thursday. Yet he is still willing to go into this 3-1 fight to bring his winning message to the American people, and he will win."

In a statement to ABC News, a CNN representative referred to moderators Dana Bash and Jake Tapper as "well respected veteran journalists" with massive experience moderating significant political arguments.

"There are no two people better equipped to co-moderate a substantial and fact-based discussion and we look forward to the debate on June 27 in Atlanta."

The event will take place in the battleground state of Georgia, starting at 9 pm ET.

In a statement released by CNN, the debate is set to unfold in the network's Atlanta studios without an audience to allow for maximum focus on the candidates' discourse. Further details regarding moderators and specific format will be disclosed at a later date.

This year's elections likely mark the most heated the country has ever witnessed, due to considerations from certain states, namely Texas, to split away from the federation.

New surveys showed Donald Trump leading Joe Biden in five key battleground states. 

According to the results, Trump is ahead in Pennsylvania (3 points), Arizona (7), Michigan (7), Georgia (10), and Nevada (12). Biden dominated with 2 points in Wisconsin.