President-elect Trump's choice for secretary of labor is coming under attack from an unlikely source: conservatives who want to see the kind of immigration crackdown Trump promised during the campaign.

When Trump announced he was tapping fast food executive Andrew Puzder to run the Department of Labor, most of the reactions fell along predictable partisan lines. Conservatives celebrated opposition to regulations like the Obama administration's overtime rule while liberals condemned his opposition to minimum wage increases, especially the "fight for $15" campaign.

But it wasn't labor unions or progressives who got the "Never Puzder" hashtag trending on Twitter. It was immigration hawks deriding the Hardee's/Carl's Jr. CEO as a proponent of amnesty and open borders.

Center for Immigration Studies executive director Mark Krikorian wrote that Puzder "put Americans last" and was "perhaps the worst person imaginable" for overseeing the guest-worker programs under the Labor Department's jurisdiction. Krikorian also described Puzder as "one of the nation's most outspoken business voices for Gang of Eight-style immigration policies."

The Federation of American Immigration Reform slammed the nomination in a statement, saying that Puzder represents a restaurant industry that "has thrived on low-wage labor, illegal workers, and which has lobbied for greater access to foreign guest workers to maximize corporate profits."

"The American people need to be reassured that the incoming Labor Secretary will not prioritize the interests of cheap labor employers over the interests of American workers," said FAIR's president Dan Stein.

Both FAIR and the Center for Immigration Studies support lower levels of immigration and greater enforcement.

At issue is Puzder's longstanding advocacy of immigration policies at odds with Trump's campaign promises. This matters because the Labor Department plays an important role in the importation of certain foreign workers and oversees guest-worker programs like H-1B for the tech sector, H-2A for agriculture and H-2B visas. Labor also has some involvement in worksite immigration enforcement.

Puzder published an op-ed calling for comprehensive immigration reform at the beginning of the Gang of Eight push in 2013. That same year he spoke at the American Enterprise Institute in favor of increasing low-skilled immigration. He signed a 2015 statement of top Republican donors calling for immigration liberalizing.

"Fixing our broken immigration system is the right thing to do," Puzder said in the statement. But his endorsed fixes are the opposite of what some Trump voters were hoping for. "Our values indicate we should be the party of immigration reform," he told the Hill in a story headlined "Top GOP donors: Be like [Jeb] Bush on immigration."

Bush has in fact expressed support for Puzder's nomination.

Puzder tweeted out a George Will column titled, "Trump's immigration plan could spell doom for the GOP." Puzder commented, "George Will gets it. An important read."

The liberal "explanatory journalism" site Vox headlined its story on the Puzder nomination "Trump's secretary of labor pick is exactly the type of pro-immigration Republican Trump campaigned against." The subhead? "Andy Puzder sounds a lot more like Jeb Bush than Donald Trump."

"President-elect Donald Trump has a known tendency to agree with the last person he spoke to," writes Vox's Dara Lind. "By naming fast-food CEO Andy Puzder his secretary of labor, Trump is guaranteeing at least one of the people speaking to him will be an advocate for Trump to flip-flop on his signature issue of immigration."

H-1B visas and guest workers have been precisely the immigration-related areas where Trump has flip-flopped the most. In a debate during the Republican primaries, he declined to back up his campaign website's criticism of a proposal by Sen. Marco Rubio, R-Fla., to triple the number of H-1Bs.

"I am all in favor of keeping these talented people here so they can go to work in Silicon Valley," Trump said. Rubio ended up pointing to some high-profile cases of H-1B abuse instead, promising companies that game the system will lose access to it.

The latest immigration flap comes after Trump nominated John Kelly to run the Department of Homeland Security. Immigration hawks generally preferred Kelly to Rep. Michael McCaul, R-Texas, but were mostly pushing for Kansas Secretary of State Kris Kobach. Kobach could still join the administration as deputy homeland security secretary or in some other role.

Immigration hawks did get their top choice for the Justice Department when Trump announced he was nominating Sen. Jeff Sessions, R-Ala., for attorney general. The restrictionist right is arguably one for three on the Cabinet posts with most influence over immigration.

Even before the new nominations, prominent immigration hawks like conservative columnist Ann Coulter and liberal blogger were publicly worrying about Trump letting them down on the issue. They argue without strong restrictionist personnel, Vice President-elect Mike Pence and House Speaker Paul Ryan could undermine Trump on immigration.

Puzder's nomination plays into these fears, even though Trump just this week publicly reaffirmed his support for key restrictionist positions, including cutting legal immigration to "hundreds of thousands" per year from the current 1 million or more.

If Republicans rally to Puzder's pro-business bona fides, however, there might not be much immigration hawks can do about his nomination. Many GOP senators are supporters of comprehensive immigration reform. The most significant exception, Sessions, is already a Trump Cabinet nominee.