Nate Silver has written a post arguing that comparisons between Obama, FDR, and LBJ are unfair because FDR and LBJ had larger Congressional majorities when they passed their major legislative accomplishments:

When F.D.R. took over the Presidency in 1933, the Democrats controlled 64 percent of the Senate seats and 73 percent (!) of the House seats, counting independents who were sympathetic to the party. And those numbers only increased over the next couple of midterms — during their peak during 1937-38, the Demorats actually controlled about 80 percent (!) of the seats in both chambers. Obama, by contrast, came into his term with 59 percent majorities in both chambers. That’s not much to complain about by the standards of recent Presidencies, but is nevertheless a long way from where F.D.R. stood during his first two terms, or for that matter where L.B.J.’s numbers were during the 1965-66 period, when the bulk of the Great Society programs were implemented.

F.D.R. and L.B.J. might have been great cleanup hitters — and you’ll get no argument from me that Obama’s aptitude at shepherding his agenda through Congress has been mixed, at best. But they basically spent the first several years of their Presidencies playing in the Congressional equivalent of Coors Field.

However, Silver neglects the differences in the composition of the Democratic Party in Congress between the three presidencies. The current Democratic caucus is more liberal and less ideologically diverse than the ones which passed FDR and LBJ’s legislation. To illustrate, here are plots of the estimated ideological distributions by party ranging from liberal to conservative for the 73rd (1933-1934), 89th (1965-1966), and 111th Congress (2009)*:

In particular, LBJ faced a widening split between Southern and Northern Democrats on both core economic issues as well as civil rights (an issue that split both parties internally at the time). He and FDR did have two major advantages relative to Obama — more moderate Republicans and fewer filibusters — but it’s not obvious they were playing at Coors Field.

* Technical note: These are kernel density plots of first dimension estimated ideal points from Common Space DW-NOMINATE. I’ve suppressed the scale on the y-axis for aesthetic reasons.