Brett Kavanaugh, associate justice of the U.S. Supreme Court, smiles as President Donald Trump, not pictured, speaks during a ceremonial swearing-in event in the East Room of the White House in Washington, D.C., on Monday, Oct. 8, 2018. Andrew Harrer | Bloomberg | Getty Images

Justice Brett Kavanaugh has only been on the bench for two months, but a controversial decision announced this week has abortion opponents starting to worry that he may not be the ally on the high court that they expected. On Monday, the court announced that it would not review two lower court decisions that temporarily banned Louisiana and Kansas from cutting Planned Parenthood's Medicaid funding. While three of the court's conservatives voted to take up the cases, Kavanaugh and Chief Justice John Roberts declined to join them, ensuring the cases would not receive the necessary four votes for review. Despite a claim of "vindication" from Republican Sen. Susan Collins of Maine, who voted to confirm Kavanaugh after he assured her that he viewed the court's abortion precedents as settled law, progressives have cautioned against reading too much into Kavanaugh's vote.

The question the cases presented was not about the legality of abortion, but instead over whether individuals have a right to challenge a state's determination that a Medicaid provider is "qualified." But opponents of abortion are already sounding alarm bells, frustrated that President Donald Trump's second nominee to the court declined his first opportunity to hear a case that could have ramifications for America's largest provider of abortion services. "There goes everyone's certainty that Kavanaugh was going to kill abortion," one poster wrote on a popular online forum for individuals in the pro-life movement. Other posts said harsher things.

'People are upset'

"I think people are upset. They are upset and it's understandable," said Travis Weber, vice president for policy at the Family Research Council, a Christian nonprofit and activist group. Weber said his group was not holding Kavanaugh's decision against him, because while the decision was "not the greatest result," it was largely procedural. Though some suspect that Kavanaugh's vote was designed to deflect criticism from the left after a brutal confirmation process, Weber said that at this point it was impossible to know for sure. "If that's what he's doing here, that's a big problem," Weber said. "We don't know that." To Nicholas Drake, pastor at Richland Baptist, a rural church in Kingdom City, Missouri, Kavanaugh's decision could not have been more disappointing. In an interview, Drake said that during the nomination process he was hopeful about where Kavanaugh would land on the issue, but that he was hearing "conflicting things." Kavanaugh's comments during his confirmation hearings gave him more reason for concern. Kavanaugh said at the time that Roe v. Wade, the landmark abortion ruling, was "an important precedent of the Supreme Court that has been reaffirmed many times." "It was clear that he was pro-life, but at the same time he seemed to be very big on the precedent, so I thought, 'Hmm,'" Drake said. "It gave me a hesitance about whether he would be able to side with the conservatives, and so far, this most recent decision proved that he hasn't." Drake said he was not as concerned by Kavanaugh's apparent break with conservatives in a death penalty case earlier this year. He said the issue was important, "because it's life," but he said that "there is a huge difference between protecting the innocent unborn and whether the state can execute someone who is proven to be guilty."

In a statement, Leana Wen, president of the Planned Parenthood Federation of America, said that the result of Monday's decision is that "our patients who rely on Medicaid can continue accessing life-saving services like birth control, cancer screenings, and STD testing and treatment at Planned Parenthood." "However, I am a doctor, and I have to look at the data – Justice Kavanaugh has a deeply troubling record when it comes to access to health care including safe, legal abortion," Wen said. "While we celebrate, these attacks won't stop."

Early skeptics

Four thousand miles away from Missouri, Matthew Norris, who follows the court closely from the United Kingdom and also opposes abortion, expressed similar misgivings. "Given what little we know about his jurisprudence on abortion, the reluctance to take the issue could indicate that he is more torn on the issue than either his critics or his supporters suggest," Norris, a Ph.D. candidate in philosophy, wrote in a message to CNBC in response to written questions.

"Nonetheless, it would be wrong to call him a solid pro-life judge. Pro-life supporters of Kavanaugh's nomination ought not take it for granted that he will protect the unborn," he wrote. While many anti-abortion groups celebrated Kavanaugh's nomination, some have been skeptical all along. For instance, the American Family Association, an influential Christian group, issued a statement following Kavanaugh's nomination in July saying it was "deeply concerned" about how Kavanaugh might rule on issues concerning reproductive rights and religious liberty. David French, a senior fellow at the National Review Institute, a conservative nonprofit, wrote at the time that Trump picked the "wrong judge" by passing over Amy Coney Barrett, an appeals court judge and a favorite of anti-abortion conservatives. To an extent, the Monday decision has proven to be something of a Rorschach test for those on both the left and right. In his blistering dissent, Justice Clarence Thomas wrote that the question the court was asked to consider "has nothing to do with abortion." "So what explains the Court's refusal to do its job here? I suspect it has something to do with the fact that some respondents in these cases are named 'Planned Parenthood,'" he wrote. Abe Hamilton, a public policy analyst for the American Family Association and its general counsel, said that the group's early concerns about Kavanaugh were "not assuaged" by Monday's decision. Hamilton said in a statement that "it is unfortunate that neither Roberts nor Kavanaugh could bring themselves to make what in any other context would have been a slam dunk to grant certiorari."

Political considerations

Andrew Napolitano, a conservative legal commentator and a judicial analyst at Fox News, said that, with the harsh dissent, Thomas, Gorsuch and Alito were "chiding their junior Catholic pro-life colleague Brett Kavanaugh." Napolitano, who has been critical of Kavanaugh in the past, suggested that Kavanaugh's decision might have been a "way to demonstrate to Dianne Feinstein that he's open-minded." But not all abortion opponents see in Kavanaugh's decision evidence for concern. Catherine Glenn Foster, the president and CEO of Americans United for Life, noted that, at this point, all the commentary on Kavanaugh's decision is just speculation. "I don't think we can necessarily make predictions based on this," she said. "I don't think it's a bellwether for whether Roe v. Wade will be overturned." Drake, the pastor in Kingdom City, said he was still hopeful — but with a caveat. "Cautiously hopeful. Not even cautiously optimistic anymore," he said. WATCH: There's now an entire government division dedicated to protecting health workers that object to abortions