Wes Nakagiri, founder of conservative political group RetakeOurGov and a vocal critic of Snyder's proposed expansion of Medicaid, said he would bring a "conservative voice" to the administration.
"Having a grassroots conservative on the 2014 ticket will energize the base of the GOP to come out and work hard on its behalf," he said in a statement.
Though gubernatorial candidates are chosen in primary elections, their running mates are picked at party conventions. It is customary for delegates to get behind the gubernatorial candidate's choice.
Yet in 2010, tea party activists insisted on a rare roll call vote for lieutenant governor even though the more moderate Snyder — after beating four more conservative candidates who split the vote in the primary — had named Calley his running mate. Fruitport businessman and tea party favorite Bill Cooper ultimately withdrew his name, but not before the convention erupted into angry chants and booing.
Nakagiri's announcement came ahead of this week's expected Medicaid expansion vote in the Republican-controlled state Senate. Days before the GOP-led House voted in June to expand the government insurance program under the federal health care law, a group of tea party and conservative activists announced their opposition to Snyder's re-election.
"There is no doubt that the expansion of Medicaid is a key component of Obamacare. Indeed, this expansion is directly at odds with the Republican Party platform," said Nakagiri, an automotive engineering manager who lives in Livingston County's Hartland Township.
Snyder has never been embraced by tea party leaders, but having to stave off a challenge to Calley may waste time and resources within the GOP that could be devoted to helping Snyder defeat likely Democratic challenger Mark Schauer.
In an appearance on public television's "Off the Record" show last week, Calley addressed the possibility of facing a challenger.
"The convention knows that I'm a conservative voice in the governor's ear," he said. "Our administration has vigorous debates behind the scenes and then we come out with united positions."
Calley, a former state representative and banker from Portland, said he will not take his re-nomination for granted but is confident he will have strong backing at the convention.
"Regular tea party voters" will look at the totality of what the Snyder administration has accomplished and be supportive, he said, because "not everybody requires that you have 100 percent agreement."
A message seeking comment on Nakagiri's announcement was left with Snyder, who has not officially launched his re-election campaign.
U.S. Rep. Justin Amash, a Cascade Township Republican who is popular with the tea party movement, took to Twitter to stand behind Calley on Monday, calling him a "great friend & ally."