The All-Star game has been moved from Truist Park to Coors Field following criticism of Georgia's new voting laws.
The Democratic senator's comments came in the wake of a mass shooting in his state on Monday.
"How dare you, Cory Gardner, misuse and abuse the memory of Uncle Jack in this grossly misleading advertisement," tweeted Kerry Kennedy.
Democrats need to gain at least four seats to take control of the Senate.
Andrew Yang and John Hickenlooper are two of several 2020 Democratic presidential candidates who joined Biden's campaign team after suspending their own.
The Colorado senator has said he will support a "qualified nominee" who will "protect our constitution, not legislate from the bench, and uphold the law," should one be put forward.
"Going into the general election, there are bigger forces in play that most people agree gives John Hickenlooper an advantage," Republican pollster David Flaherty said.
The GOP currently holds a three-seat majority in the Senate—and they have to defend more than 20 seats in the 2020 cycle.
Hickenlooper plans to announce his withdrawal Thursday morning; the Democrat from Colorado was not among the top contenders in the crowded 2020 field.
"That is not what this country was founded upon. This is not what we've been successful upon," former Republican Representative Diane Black argued.
"Do you ever think, I just want to break out and be honest once in a while, or no?" Carlson asked.
"Join me and we'll repair the damage done to our country and be stronger than ever," the former Colorado governor said.