This is surprising (via Ari Berman).

For those keeping track, Rep. Sensenbrenner, a Republican, worked mostly with Democrats on the Voting Rights Amendment Act, which was seen by Democrats as a fairly watered down measure to restore a preclearance regime for voting changes which were lost when the Supreme Court decided Shelby County v. Holder. The measure has gone nowhere, in part because it was thought that Rep. Eric Cantor would have pushed it (but he lost in the 2014 Republican primary).

In response to lack of movement on this legislation, Democrats pushed the Voting Rights Advancement Act, which is stronger in terms of which states get covered and how.  Sensenbrenner would not sign on to this one. But now Senator Murkowski becomes the first prominent Republican to do so.