CHICAGO (CBS) — Though previously opposed to Donald Trump in favor of Wisconsin Gov. Scott Walker, Joe Ricketts has promised to donate to the Republican presidential nominee’s campaign.

According to The Wall Street Journal, Ricketts has promised to donate at least $1 million to help Donald Trump win the presidency. Joe Ricketts is the founder of TD Ameritrade Holding Corp., and is the father of Chicago Cubs chariman Tom Ricketts. Tom’s brother Pete Ricketts is the republican Gov. of Nebraska. Gov. Ricketts endorsed Trump in May.

“The Ricketts decided they could not sit back and watch Hillary Clinton become the next president of the United States,” Brian Baker, political strategist for Joe Ricketts, told The Wall Street Journal. “Even though the Ricketts supported other candidates during the primary, they believe it is time to unite behind the nominees … This is all about helping Republicans win in the fall.”

In February, Donald Trump sent a negative tweet about the Ricketts family, writing, “I hear the Rickets family, who own the Chicago Cubs, are secretly spending $’s against me. They better be careful, they have a lot to hide!”

I hear the Rickets family, who own the Chicago Cubs, are secretly spending $'s against me. They better be careful, they have a lot to hide! — Donald J. Trump (@realDonaldTrump) February 22, 2016

In January, Marlene Ricketts contributed $3 million to an anti-Trump political action committee.

“It’s a little surreal when Donald Trump threatens your mom,” Tom Ricketts said in response to Donald Trump’s tweet. “The fact is whether it’s my mom or my dad on his Ending Spending stuff or my sister on marriage equality issues or my brothers and what they do or what we do with the team, we are pretty much are an open book. We stand up for what we believe in. We support the causes we think are important. That is what America should be. That is who we are.”

At the time, Tom Ricketts also noted that his focus is the Cubs winning the World Series.

“What other people in my family do is their day job,” he said. “I support everything they do. It’s just not my focus. Once again, the stuff that happens on the political side is not my daily focus.”

CBS Chicago has contacted Tom Ricketts, though he has not replied. He has yet to state whether he shares his father’s change of heart.