That is because their bench for their 1/2 of the Uni-Party sucks way worse than ours ( yes I have been saying for quite a while our vaulted 16 aren't all that good except for a handful of them ).
Look at the at their old horses ready for the glue factory in the Senate. The Democratic party is in horrible shape IMHO....
Republicans have a bench. Democrats have a stool. Or a two holer