MADISON, Wis. -- State lawmakers have still yet to agree on drunken driving legislation, but they hope to do so by the end of the year.

Both houses have passed their own versions of a bill that would make a fourth drunken driving offense a felony in some cases and require ignition interlocks for repeat offenders and first time drunken drivers with a blood-alcohol content over 0.15.

The differences between the Assembly and Senate lie in how to pay for increased jail costs and treatment options.

But the session ended last week without compromise.

"The responsible thing is to pass good, solid legislation dealing with drunken driving reforms and then find a way to pay for it, and that's what we did in the Senate, and I think the Assembly just needed some time to take a look at it," said Sen. Jon Erpenbach, D-Waunakee.

"I don't want to jump ahead of legislative leadership here but I strongly encourage the two houses to compromise on the two versions and to get a bill, and if that bill is ready to be passed I certainly will include it in a special session," said Gov. Jim Doyle.

The state Assembly has indicated its willingness to go into special session to take up the legislation as well.