Florida Sen. Marco Rubio has been widely recognized as a rising star and contender for the 2016 presidential nomination, but his struggle in getting an immigration reform bill passed, particularly the ire it has drawn from the more conservative wing of the GOP, has made clear just how difficult his path to mainstream success will be.

The latest example was Sarah Palin’s Facebook diatribe on Monday, in which the former Alaska governor and one-time vice presidential candidate attacked the immigration reform bill passed by the Senate as “amnesty” and called out Rubio for being “disingenuous” for saying that a “vote for this bill is a vote for security.”

Palin has been largely out of the spotlight since resigning as governor and deciding against running for president herself in 2012, but her voice still draws attention as a barometer of right-wing, tea party sentiment. And those are the very folks that Rubio seems to be having trouble with in his high-profile push for immigration reform.

Rubio and other Republicans who rode into Washington on the wave of discontent in the 2010 midterms did so in part because of the public’s frustration with the Affordable Care Act’s politics. That bill, commonly referred to as “ObamaCare,” spurred Republican voters to go to the polls and became the poster child for tea party anger with “Big Government.”

But Palin has now accused Rubio and others of following the same playbook with immigration reform, saying “Just like they did with Obamacare, some in Congress intend to ‘Pelosi’ the amnesty bill.”

She went further in her comparisons, adding that “They’ll pass it in order to find out what’s in it. And just like the unpopular, unaffordable Obamacare disaster, this pandering, rewarding-the-rule-breakers, still-no-border security, special-interests-ridden, 24-lb disaster of a bill is not supported by informed Americans.”

But a report released two weeks ago by Democratic and Republican pollsters found the opposite: “overwhelming, bipartisan support for the bill” in 29 states surveyed.

Palin’s criticisms seemed centered around her contention that the “bill isn’t about fixing problems; it’s about amnesty at all costs.” The success of a stronger border security amendment helped achieve a 67-27 vote to move to avoid a filibuster and proceed to a vote on the bill itself. The bill is seen as likely to pass when a final vote is taken up in the Senate later in the week.

Sen. John McCain (R-AZ), who picked Palin as his running mate in the 2008 presidential campaign, is one of the authors of the immigration reform bill and has stood by it. He told The Arizona Republic that this is “the crucial week” in determining whether it succeeds or not.