With Senate Finance Committee Chairman Max Baucus (D-Mont.) retiring, Ron Wyden of Oregon is next in line to hold the gavel. The wonkish Oregon senator is better-liked than Baucus among liberals, but he also has a tendency to break with his own party -- including a high-profile attempt at Medicare reform. And he has his own tax reform plan. Here's what you need to know.

Ron Wyden. (Chip Somodevilla/Getty Images)

1. He cares about tax reform: Without reelection to worry about, Baucus is expected to put more energy into getting tax reform done. Assuming he succeeds, Wyden won't oversee that overhaul -- but he's likely to be involved. Like Baucus, Wyden is interested in a complete overhaul of the tax code rather than just the corporate tax reforms favored by the White House and some Democrats.

Wyden's proposal, worked out with Sen. Dan Coats (R-Ind.), includes a flat 24 percent corporate tax rate, eliminates the alternative minimum tax, cuts three out of six income tax brackets, triples the standard deduction, and eliminates tax breaks and loopholes. He would allow corporations to bring profits back into the U.S. at a temporary low rate, but after that they would not be allowed to defer taxes on overseas income.

2. He wants to tackle Medicare. Wyden has named Medicare as a top priority for the Finance Committee. Again, this is something Baucus could take on in the next two years. But Wyden has a long history of attempting to reform Medicare; as far back as 1997 he attempted to reform the program with then-Sen. Phil Gramm (R-Texas). Along with Rep. Paul Ryan (R-Wis.) he engaged in a high-profile attempt at a Medicare compromise, one that included the private plans Republicans favor but kept traditional Medicare as an option, built in consumer protections and protected seniors if costs get too high.

Wyden was also working on health-care reform since way back when. He tried repeatedly to get an amendment put into the Affordable Care Act that would have made it significantly more ambitious by letting people covered by their employers opt out and go on the health-care exchanges. He blamed Baucus for keeping that amendment from getting a vote in the Senate Finance Committee -- while the White House demanded Wyden "stay on message."

3. He likes working with Republicans. Coats and Ryan are far from only GOP partners on Wyden proposals. The phrase "comprehensive, bipartisan solution" is so common in his office that it's become an inside joke. He's worked with Sen. Orrin Hatch (R-Utah) and former Sen. Bob Bennett (R-Utah) on health-care reform, former Sen. Scott Brown (R-Mass.) on an individual mandate opt-out, Sen. Lisa Murkowski (R-Alaska) on campaign finance reform, Rep. Jason Chaffetz (R-Utah) on GPS privacy, Sen. Chuck Grassley (R-Iowa) on secret holds and former Sen. Judd Gregg (R-N.H.) on a similar tax overhaul. He was also the only Democrat to join Sen. Rand Paul's  (R-Ky.) filibuster on drone policy.

4. Like Baucus, he can make Democrats angry. Wyden's bipartisan instinct has irritated some of Wyden's fellow Democrats. His Medicare proposal in particular ruffled feathers. During the 2012 campaign he had to distance himself from Ryan when the vice presidential nominee started citing their work together on the campaign trail.

"A common view of Wyden within his own caucus is of a man who holds himself out as an intellectually superior renegade who is above the constraints of politics," the Post's Jason Horowitz wrote at the time. "That self-regard, and a tendency toward peevishness, sometimes leads him to stake out positions that are politically inconvenient to his party."

Wyden is also not afraid to criticize the White House when he thinks they're wrong -- on anything from bank bonuses and stimulus to drone warfare. There's enough Wyden skepticism to produce some chatter that Sen. Chuck Schumer (D-N.Y.) will get the Finance gavel instead, although that's considered unlikely.

5. But liberals still like him. At least, more than they like Baucus. Early in his career he helped run an Oregon chapter of the Gray Panthers, a liberal lobbying group for senior citizens. He's skeptical of chained CPI, a less generous benefit formula for Social Security. He was a leader in the fight against SOPA and PIPA, two piracy bills very unpopular with the progressive online community, as well as warrantless domestic surveillance and the Patriot Act. Unlike Baucus, he's a reliable Democratic vote on issues like expanded background checks for guns.

And here's one thing you don't need to know but is interesting nonetheless -- his wife is co-owner of New York's famous Strand Bookstore.