Paul Ryan has Mitt Romney beat when it comes to most policies favored by the right flank of the Republican Party. But on certain issues, particularly union rights, Ryan is more liberal than Romney.
According to Jack Craver of Madison, Wis.-based the Capitol Times, Ryan's position supporting the preservation of the Davis-Bacon Act won him the support of Wisconsin labor unions. Under that law, for federal projects contractors must pay laborers the “prevailing wage” of the location of the project. Groups like the International Union of Operating Engineers have given Ryan support in his congressional bids for that reason.
Romney, on the other hand, has said that on "day one, I will end the government’s favoritism towards unions on contracting on federal projects,” and try to repeal Davis-Bacon.
Craver writes that Ryan's support might have something to do with his family's business:
Some progressive commentators linked Ryan’s support for Davis-Bacon to his family’s Janesville construction business, Ryan Incorporated Central, a union company that employs dozens of IUOE members. If Davis-Bacon were repealed, the company would likely be underbid on many federal contracts from non-union firms that pay workers less.
Similarly, Ryan has taken a (slightly) less hard-line position than Romney on anti-union right-to-work laws. Romney has indicated that he would pass a national right-to-work law, while Ryan's camp says he would prefer to leave it up to the states.