MADISON, Wis. (CBS 58) -- David Crowley, Democratic candidate for governor, is in California for a fundraiser with former Vice President Kamala Harris and actor Sean Penn. This has drawn criticism from Republicans, but according to one expert, this practice is fairly common.

Kamala Harris was just in Michigan last week campaigning with the Democratic candidate for the U.S. Senate, Abdul El-Sayed. Experts say both sides utilize political connections from outside the state.

Republican gubernatorial candidate Tom Tiffany posted the flyer announcing the fundraising event on X. He criticized Crowley for fundraising in a different state. In a statement, he said the following.

“Self-avowed socialist Francesca Hong is holding more events across Wisconsin than David Crowley while he flies off to Washington, D.C., and California to raise money with wealthy donors and Kamala Harris. I am traveling Wisconsin, talking directly with voters, and laying out a clear agenda to cut taxes, return the state surplus to taxpayers, and lower everyday costs. Wisconsin deserves a governor focused on Wisconsin, not one outsourcing his campaign to a socialist while chasing checks in Washington and California."

Mordecai Lee, political science professor emeritus at UW-Milwaukee, says politicians often reach out to donors out of state, especially if they have deep pockets.

“When Democrats or Republicans are willing to accept money from out of state, it’s because they need to be major players, if only to buy TV advertising,” Lee said.

Lee added events like the one Crowley is attending in California aren’t uncommon, especially in highly competitive races. When it comes to what voters think, Lee says it’s hard to know. 

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“We, as Wisconsinites, have got to realize that Wisconsin voters insist on being unpredictable,” Lee said. “So how will Wisconsin voters react to a millionaire in Illinois versus a millionaire in California? Ask again after the election and then we will know if either of those criticisms ever had any traction.”

Money for ad buys is vital to a campaign, which is why events like this one take place nearly every election cycle.

“It’s important to remember that really, money is the mother’s milk of politics. In other words, it’s very hard for someone to be a successful politician, to win an election, without a decent amount of money,” Lee said.

We reached out to the Crowley campaign for comment, and while Crowley himself didn’t reply, his communications director did -- and he didn’t hold back on highlighting the billionaires that have donated to the Tiffany campaign.

"Congressman Tom Tiffany has no business lecturing anyone about fundraising when three billionaires have funneled nearly $10 million into his campaign and outside groups like Richard Uihlein's super PAC and the Koch network have poured in more than $15 million more. They know he's a sure bet, since he already voted to give the wealthiest Americans tax breaks while cutting Medicaid for Wisconsin families. Whether it's billionaires or Donald Trump, Congressman Tom Tiffany works for them; David Crowley works for you."- Philip Shulman, communications director, Crowley for Wisconsin

Crowley has been trailing Tiffany in fundraising. The next campaign finance reports drop on Oct. 1, when we will get a better picture of where each side stands financially.