(CNN) The technical term is "asymmetric polarization."
It means that one political party is getting more partisan (or polarized) than the other -- or that one side is moving closer to its ideological pole than the other.
It's what has happened in Congress over the last five decades, according to a report from the Pew Research Center examining roll call votes of lawmakers beginning in the early 1970s.
Using a system that ranks members of Congress from -1 (most liberal) to 1 (most conservative), Pew found that the average Senate Democrat (-.06) and House Democrat (-.07) have grown only marginally more liberal between the 1970s and today.
The average Senate (+.28) and House Republican (+.25) have, however, grown significantly more conservative over that same period.
As Pew's Drew DeSilver wrote of the findings: "Both parties have moved further away from the ideological center since the early 1970s. Democrats on average have become somewhat more liberal, while Republicans on average have become much more conservative."
This is not a new trend. As far back as 2012, political scientists Norm Ornstein and Thomas Mann identified the drastic rightward lurch of the Republican Party in Congress.
"The GOP has become an insurgent outlier in American politics. It is ideologically extreme; scornful of compromise; unmoved by conventional understanding of facts, evidence and science; and dismissive of the legitimacy of its political opposition.
"When one party moves this far from the mainstream, it makes it nearly impossible for the political system to deal constructively with the country's challenges."
And that was written a decade ago -- long before there was a President Donald Trump, a Sen. Josh Hawley or a Rep. Marjorie Taylor Greene!
Not surprisingly, the ideology of Congress as a whole has also moved rightward. The House (+.13) and Senate (+.14) are both demonstrably more conservative than they were in the 92nd Congress back in 1971-1972.
What those findings mean is that not only have Republicans moved faster and further to the ideological right than Democrats have gone to the left, but also that they have made the entirety of the House and Senate more conservative over the past 50 years.
The Point: It is true that Democrats have grown slightly more liberal over the past five decades. It is also true that Republicans have grown FAR more conservative over that same time and, in so doing, have moved the overall ideological center of the House to the right as well.