Government Publishing Office and Library of Congress provides XML formatted bills and all their amendments and a feed of all changes to every bill.
Oh and on the topic of party politics, Bill Clinton was the one who had them put things online in the first place with the GPO Electronic Information Access Enhancement Act, and Barack Obama and the Democrats expanded it via American Recovery and Reinvestment Act of 2009 - not the do-nothing Republicans.
That's not really the right picture.
Congress.gov, originally THOMAS.gov, was a product of the Republican Contract with America take-over of Congress in the mid 1990s. Republicans in Congress, including Rep. Issa for example, were helpful in expanding the information that Congress publishes publicly. In the last 15 years, efforts to make Congress publish more and better-structured information have been relatively bipartisan and, mostly, led by nonpolitical staff. I would not describe Democrats as having been the ones to have exclusively created the access to congressional information that we have today, although Democrats in recent years have led on government transparency and accountability issues generally, beyond the Legislative Branch.
Changes that have required legislation have, as far as I'm aware, not really been influenced by the President, other than being signed into law, since they are Legislative Branch concerns and not Executive Branch concerns.