There are two reasons commonly cited for the fact that far fewer Democrats than Republicans are running for president in 2016. One is that Hillary Clinton was (and largely still is) considered a formidable candidate that, for most politicians, isn't worth the energy and money to try and defeat. The other is that the Democrats, after a few bad election cycles, have a very small political "bench" -- meaning that there aren't as many politically talented and successful candidates on the left as there might otherwise be.
Our Dan Balz made this point in the wake of last November's crushing Democratic defeat. Balz noted the scattered Democratic talent on Capitol Hill -- and then looked west. "The more serious problem for Democrats," he wrote, "is the drubbing they’ve taken in the states, the breeding ground for future national talent and for policy experimentation."
Balz pointed to data from the National Conference of State Legislatures, showing that Republicans had unified control -- both chambers of the legislature and the governorship -- in nearly half of the 50 states.
There's another way to look at that. The NCSL's annual breakdown of the composition of each state's Senate and House or Assembly goes back to 2009, when President Obama was inaugurated. Since then, the ratio of Republicans to Democrats has tilted to the right in nearly every Senate and nearly every legislature.
(This compares the number of Democrats in each legislative body to the number of Republicans. It excludes any independent or minor party elected officials and doesn't include vacancies. NCSL data is generally from January of each year. It also excludes Nebraska, which has a non-partisan, unicameral legislature.)
Part of the reason for that Republican shift is that the major election cycles since 2009 have been brutal for the Democrats. In both the 2010 and 2014 midterms, the electorate was very unfriendly to the party, as poll results indicate. In 2012, it was about split. And in the off-year elections during which some states hold legislative races, turn-out often favors the Republican Party.
Only between 2011 and 2013, and only in state Houses did the Democrats make in-roads in more states than Republicans. Between 2009 and 2011 and between 2013 and 2015, the Republicans made gains in far more states.
Overall, of the 98 state senates and houses/assemblies, the Republicans saw gains in 40 upper chambers and 45 lower ones. Meaning far fewer elected Democrats, and a smaller bench. Many of those Democrats are necessarily from swing districts, as our Aaron Blake pointed out last year -- the sort of districts from which parties like to recruit.
How many Democrats are we talking about? According to the NCSL data, there were 4,082 Democrats in state senates and state houses in 2009. In 2015, there were 3,163 -- a decrease of 22.5 percent.
That's 900-plus fewer Democrats to move up the ladder.