Ignoring the political reality of Presidential veto power they will whine and complain about the GOP no matter what it does!
A liberal party winning is not, by definition, a good thing. The GOP establishment has a history of cooperation with the hard left, even more openly so under Obama. It is not a case of “no matter what it does” but the history of what it does.
And vetoes can be overridden with the Democrats’ help—if the GOP were indeed concerned about the country and worked on the blue-dog tendencies that some of the Dems would possess still. Remember, it is the establishment GOP types themselves claiming that they cannot act because of a presidential veto.