Supreme Court Chief Justice John Roberts’ role as the court’s new swing vote has become abundantly apparent in recent weeks, as he has been the deciding justice in several high-profile 5-4 decisions in which he sided with the court’s liberal bloc -- providing hope for Democrats and angering Republicans.

The jurist kept court watchers on their toes yet again this week, siding with the conservatives in a tight decision that delivered a win for the school choice movement on Tuesday.

But in Monday’s decision in June Medical Services v. Russo, Roberts sided with the liberal members to rule against a Louisiana law restricting who can perform abortions, upholding precedent from a similar case in 2016 in which he was on the other side. This followed his vote in rejecting the Trump administration’s attempt to rescind DACA and his vote in a 6-3 decision that prohibited employment discrimination based on sexual orientation and gender identity.

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"The Supreme Court’s entering Buffalo Springfield territory: 'There’s something happening here,'" Senate Minority Leader Chuck Schumer, D-N.Y., said after Monday’s ruling.

Sen. Ted Cruz, R-Texas, observed a similar trend after the DACA decision but was far less enthusiastic about it.

“Over recent years, more and more, Chief Justice Roberts has been playing games with the court to achieve the policy outcomes he desires,” Cruz said on the Senate floor, before citing past instances of what he called "sleight of hands" by Roberts, adding: "This is becoming a pattern."

Sen. Bernie Sanders, I-Vt., celebrated Monday’s ruling while pointing out that it went against Republican political preferences.

“This is a major victory for reproductive rights. The Supreme Court has confirmed it over and over again: the decision to get an abortion is a constitutional right, whether extremist Republican legislators like it or not,” Sanders tweeted.

Well-known liberal law professor Laurence Tribe, who taught Roberts at Harvard, expressed pride for his former student after Monday’s decision.

“Adding the Louisiana abortion decision to the DACA decision and the LGBTQ decision makes me especially proud of my former constitutional law student, Chief Justice John Roberts,” Tribe tweeted.

Roberts' history of separating himself from the court’s conservative contingent in key cases goes back years.  In 2012, by siding with the liberal wing and reinterpreting an individual mandate as a tax, he allowed ObamaCare to be found constitutional. Additionally last year he joined with liberals again in shutting down the Trump administration’s efforts to add a citizenship question to the census.

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The recent decisions, however, appear to have particularly struck a chord. President Trump called them “shotgun blasts into the face of people that are proud to call themselves Republicans or Conservatives.” Even before Monday’s abortion case, Trump indicated that he was not confident in the current makeup of the court, despite the majority of justices being Republican appointees.

“The recent Supreme Court decisions, not only on DACA, Sanctuary Cities, Census, and others, tell you only one thing, we need NEW JUSTICES of the Supreme Court,” Trump tweeted earlier this month.

Yet Roberts is far from the first justice appointed by a Republican president to drift from the conservative bloc, and a number of Republican selections have famously moved even further left.

Justices Anthony Kennedy and Sandra Day O’Connor, both recent examples of swing vote justices, were appointed by President Ronald Reagan. Justice David Souter, who was chosen by President George H.W. Bush, often sided with the court’s liberal contingent.

In 1992’s landmark Planned Parenthood v. Casey, the Supreme Court upheld the right to an abortion in a 5-4 decision. All five majority votes – O’Connor, Kennedy, Souter, John Paul Stevens, and Harry Blackmun -- were appointed by Republicans. The opinion in Roe v. Wade, which first established abortion as a right, was written by Blackmun, who was tapped for the Supreme Court by President Richard Nixon. The late former Chief Justice Earl Warren, nominated by Dwight Eisenhower, also faced criticism from conservatives for the court's decisions.

Several conservatives have expressed fear that Roberts is not even a swing vote, and that he has gone full liberal.

“John Roberts is an empty black robe who wants to be loved by liberals who believe in legislating from the bench,” said former Arkansas Gov. Mike Huckabee. “Mr. Chief Justice, if you want to be a legislator, resign and run for Congress. But at any rate, just resign!”

“John Roberts didn’t ‘side with’ the liberal wing of the Supreme Court, HE IS A LIBERAL,” tweeted Fox News contributor Dan Bongino.

Despite the attention to Roberts’ recent left-leaning votes, however, the chief justice has on many occasions remained with conservatives in 5-4 decisions. According to statistics compiled by SCOTUSBlog, the court’s October 2018 term featured 17 cases that resulted in 5-4 decisions where all four liberal justices voted together. Of these, Roberts turned out to be a deciding vote in 10 of them, sticking with his fellow conservatives seven times and voting with liberal justices three times.

On Tuesday, Roberts sided with conservatives, resulting in the 5-4 decision in the school choice case that said a clause in Montana's state constitution forbidding aid to schools controlled by a "church, sect, or denomination" violated the U.S. Constitution's Free Exercise Clause because it prevented religious schools from participating in an aid program that would have provided tax credits for scholarships at private schools.

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The Supreme Court still has nearly a dozen cases left to decide this term, with several having significant political implications. Their issues include whether states can force members of the Electoral College to vote in accordance with the state's popular vote, and whether President Trump's tax returns can be released to House committees or Manhattan prosecutors.

Fox News' Adam Shaw contributed to this report.