If by liberal and progressive you imply in the use that they tend to vote Democrat, the answer should be yes, but not by as large a margin as is usually implied/guessed.
As an example we can take the exit polls from the 2012 presidential race, we see that while Obama won in most of the educational categories (look at the NYTimes) he did win by significantly higher margins in the postgraduate part of the population (+13 percentage points), lost college graduates by 4%, and won people with some college by 1%.
| Who | % Population | Obama | Romney | Obama's Margin |
| People with no higher education at all | 53% | 51% | 47% | 4% |
| People with some college | 29% | 49% | 48% | 1% |
| College educated | 29% | 47% | 51% | -4% |
| Postgraduate | 18% | 55% | 42% | 13% |
The same holds true for the Senate races where the Democrats control "safely" the potsgraduates.
Or you can look at a typical red state (Texas) where the only group democrats carried consistently are postgraduates.