Tuesday could be a big big day for the Milwaukee Bucks.

The power-backed bill providing $250 million in public aid to build a new arena for the Milwaukee Bucks in Downtown Milwaukee moves to the Wisconsin State Assembly, with a more uncertain future than it had in the Senate.

The bill passed a week ago,  21-10, in the Senate, a margin that surprised most experts. The common wisdom was that it was going to be close and instead it was a tidal wave.

That momentum may continue in the assembly Tuesday but there are hints in both parties that may send the bill back to the Senate.

Republican rumblings come from Speaker Robin Vos, who leads the GOP, which controls the house by a 63-36 margin. Vos has been saying that he need 14 or 15 Democratic votes (mainly from Milwaukee) to pass the bill in order to provide cover for Republicans who are fearful of voter backlash if they vote to approve the measure.

Democratic rumblings are coming from representatives who are trying to walk down the middle of the road. Most of them want the Bucks to stay in Milwaukee, but there is some push-back from several community groups.

In addition, Democrats are still aggravated that there was no party input in crafting the measure.

Minority Leader Rep. Peter Barca said that he expected members to have a number of concerns that could be addressed in amendments.

"Unlike the Republicans, who generally vote as a bloc on everything, except when you get down to tough votes like this, we always encourage people to vote their districts," Barca said.

It’s expected that there will be amendments proposed to the bill that would provide for promised minimum wages for employees, women and minority commitments to the construction package.

For example, Milwaukee Rep. JoCasta Zamarripa wants a provision that allows workers in the new arena the right to organize. If Vos needs to add an amendment like that to the package it would kill the bill once it goes back to the Senate.

Republican opposition will come from many areas, including the Fox Valley where the massive construction project remodeling Lambeau Field was paid for exclusively with local taxes. Voters there would wonder why they were being asked to support a Milwaukee project and representatives from the Green Bay area, for example, would have a hard time explaining their vote come election time.

While all this horse trading goes on the Bucks are sitting on the sideline, if not silent then at least sticking to their claims that the arena is needed and that they will cover any cost overruns on the project.  They don’t want to comment on the vote or the heavy lobbying that’s going on.

If there are any changes to the measure it will go back to the Senate for approval. If the Senate can’t approve, it will go to a conference committee to hammer out a bill acceptable to both houses. All of those delays will move us closer to the brink of a deadline of fall to get a shovel in the ground.

But former owner Sen. Herb Kohl said Friday that he was sure the arena would be built. Kohl saw a lot of political machination during his years in the United States Senate and understands how much torture can come down during the negotiating process.

One thing to keep in mind is that the legislators want to get out of Madison for the rest of the summer. Sending the bill back to the Senate would delay their departure so Assembly Republicans may just vote down all Democratic amendments and force a vote on the bill. It would put Milwaukee Democrats in a tough position of voting against the package.

Once this thing passes, perhaps the toughest thing will be to track down Gov. Scott Walker to sign the measure.

One thing obvious is that Tuesday is a very important day in the future of the Milwaukee Bucks. And it would be great if they just passed the darn thing and went home to rest up for the big issues facing them when they come back.