Trump chose Todd Ricketts, an outspoken opponent of Trump's presidential bid, as his deputy commerce secretary.
At a rally in Nebraska that month, Trump took a jab at Todd Ricketts.
Announcing Todd Ricketts' selection this morning, Trump called him "an immensely successful businessman with unparalleled knowledge of the finance industry."
Trump went on to praise the work that the Ricketts family has done with the Cubs, the reigning World Series champions, even though he previously criticized their handling of the storied franchise.
In the announcement, Trump said, "The incredible job he and the Ricketts family did in the purchase and turnaround of the Chicago Cubs — one perfect step after another, leading to the world championship — is what I want representing our people."
But he didn't always felt that way. During the campaign, when some members of the Ricketts family were funding super PACs that spent millions of dollars against Trump, he fired back. In February, Trump tweeted that the family was "secretly spending $'s against me. They better be careful, they have a lot to hide!"
When asked what he meant by that during a meeting with The Washington Post's editorial board in March, Trump said, "It means that I'll start spending on them. I'll start taking ads telling them all what a rotten job they're doing with the Chicago Cubs."
Todd Ricketts comes from a wealthy politically active family with deep connections.
Todd Ricketts' brother Tom Ricketts is the chairman of the Cubs, and Todd Ricketts, Pete Ricketts and their sister, Laura Ricketts, are members of the team's board.
Pete Ricketts is in his first term as the governor of Nebraska.
At several points during the presidential campaign, Todd Ricketts and his parents were active in trying to stop Trump from becoming president.
Todd Ricketts was a finance co-chairman for Walker's failed presidential bid. After Walker dropped out, Ricketts reportedly got involved with the anti-Trump Our Principles PAC, which released ads against Trump.
Tom Ricketts was asked about Trump's tweet during a news conference relating to the Cubs.
"It's a little surreal when Donald Trump threatens your mom," Ricketts said, according to CSN Chicago, an NBC affiliate.
"The fact is, whether it's my mom or my dad on his Ending Spending stuff or my sister on marriage equality or my brothers and what they do or what we do with the team, we're pretty much an open book," he added.
"We stand up for what we believe in. We support the causes that we think are important. That's what America should be. That's who we are," the site says.