Donald Trump is in the swing state of Wisconsin this weekend, where he didn’t hold back from yet another dig at his opponent’s intelligence.

“Joe Biden became mentally impaired Kamala was born that way,” Trump said at a rally in Prairie du Chien, Wisconsin.

Also, taking the opportunity to slam Harris’ border policy once again, promising to deport undocumented migrants should he be elected.

“Kamala's Allegiance is to illegal aliens and foreign migrants,” Trump said.

“We have to get these people out. We got to get them out of here. Okay, we got to get them out fast.”

Harris is defending what she maintains is a tough-on immigration stance after a visit to the U.S.-Mexico border.

“As president, I won't only bring back the border security bill that Donald Trump tanked. I will do more to secure our border,” Harris said at a campaign event in Arizona.

It comes as polls show both sides are virtually tied in the battleground states.

But overall, Harris is leading across the national averages.

Women and under-45s lean heavily towards Harris, while Trump holds a large margin in the over-65 age group.

Both parties are ramping up their campaigns with fresh ads.

The Harris campaign attempted to reel in male voters, with The Lincoln Project posting a ‘Choose Change’ video that said, “Kamala Harris has more courage, more honour, more guts than this guy ever had.

“It's time to be a man and vote for a woman.”

The Trump Campaign has released an ad accusing democrat leaders of using “violent rhetoric” in the wake of the second assassination attempt on the former president.

So, with just 37 days to the election, both candidates are determined to leave nothing on the table.