The atmospherics offered plenty of clues, but the numbers don’t lie: The House was an even more polarized and partisan place last year than it was when the tea party class of Republicans took over the place two years before. And that’s in part because those lawmakers have grown even more antagonistic to President Barack Obama’s agenda — and even more willing to toe the party line.  

That is among the central takeaways from CQ Roll Call’s analysis of 2013 congressional voting patterns , the latest installment in an annual study that began six decades ago.  

While Obama got his way on 57 percent of the congressional votes on which he staked a position, a fifth-year success rate exceeded only by George W. Bush among the past four re-elected presidents, that was almost entirely because of a record amount of support from his Democratic colleagues running the Senate.  

In the House, Obama had his way on just 21 percent of the votes he clearly cared about, and that was because the average member of the Republican majority voted his way only 12 percent of the time, the smallest measure of presidential support any caucus has ever recorded for a Democratic president.  

Twelve percent was also the exact amount of support Obama received from the 65 members who remain from the Class of 2010. (Eighty GOP members who had never before served in Congress were elected that year.) But it’s notable that the median went down a whopping 9 points since 2011, the first year those lawmakers were in Washington.  

In other words, the group who voted against Obama 4 out of 5 times as brand-new freshmen disagreed with him 7 out of 8 times as first-year sophomores. The substance of the votes taken over the two years was different, so I can’t make a precise apples-to-apples comparison. But the trend would seem to contradict a conventional wisdom about the modern Congress: Even those who arrive with the most revolutionary fervor tend to buff away some of their roughest ideological edges after a couple of years.  

In fact, 30 of those elected in the tea party wave saw their presidential support scores decline by more than 10 points from 2011 to 2013, suggesting that many have concluded they are safe in shifting their voting patterns further to the right now that they have secured their first re-election. The steepest plunges belonged to a pair of the bigger upset winners of 2010: Ohio’s Bill Johnson backed Obama just 9 percent of the time last year, down 17 points from his first year in office; the drop by North Carolina’s Renee Ellmers was 16 points.  

By contrast, only two members of that class backed Obama more often in 2013 than in 2011. The scores edged up only a few points for both the iconoclastic Justin Amash of Michigan and the electorally imperiled Chris Gibson of New York. (Rothenberg Political Report/Roll Call rates his race , in territory Obama carried in 2012, as Tilts Republican.)  

The significant drop-off in support for Obama among the Class of 2010 is echoed, if far less dramatically, in CQ Roll Call’s studies of party unity — how often members stick with the bulk of their caucus on roll calls in which a majority of Republicans are on one side and a majority of Democrats are on the other. (Thanks for number-crunching help are due at this point to vote studies major domo John Cranford and researchers Ryan Kelly and Jay Hunter.)  

People with an eye on the Capitol every day won’t be surprised to learn that 69 percent of all the 2013 votes in Congress fell mostly along party lines, a number exceeded less than a handful of times since the start of the Eisenhower administration. But, at a time when it often appeared that Speaker John A. Boehner was struggling to hold his troops together, the average House Republican stayed in the fold on 92 percent of those votes — a record level of party unity for that caucus. The number of times the group was unanimous also was in record territory, another reflection of how GOP leaders put a priority on proposals that would unify the troops.  

And sophomores were among the most likely to back their party. Their median party unity score was 96 percent, an increase from their 94.5 percent average during the group’s first year in office.  

Five of them supported Obama often enough and strayed from the party line often enough to make those Top 10 lists: Amash, Gibson, New Yorkers Richard Hanna and Michael G. Grimm, and the retiring-after-just-two-terms Jon Runyan of New Jersey.  

Still, the takeaway about the Class of 2010 is tough to dispute: They have become a bit more partisan and markedly more confrontational since the first year they had voting cards. Given that the numbers are pushing close to the statistical extremes, these are trends that will be tough to continue, but are sure to bedevil Boehner and Obama in the meantime.