Frustrated lawmakers are threatening to scrap a plan to send millions in state tax dollars to Rochester to support Mayo Clinic's downtown makeover.

The "House and the Senate have literally moved...heaven and earth to accommodate the Mayo proposal," House Taxes Committee Chairwoman Ann Lenczewski announced during Thursday morning's tax conference committee. "I will share my frustration.. I'm comfortable waiting until next year."

The House and Senate had agreed to support Mayo -- the state's largest private employer -- as it launched its multi-billion dollar Destination Medical Center expansion. Mayo is planning to expand its facility and bring in billions of dollars in private investment to turn Rochester into a destination city in its own right.

But beyond the $585 million in state and local tax support for new infrastructure around the project, lawmakers say Mayo officials were still pushing for more concessions. Lenczewski, DFL-Bloomington, pushed back, blasting: "other entities who continue to believe they are going to decide what's going to happen" to the Destination Medical Center."

Mayo isn't in charge, Lenczewski essentially said. "The 10 of us" on the conference committee are....I'm at my limit and I'm happy waiting until next year."

"We're 99.9 percent of the way and we're still hearing that the Mayo has some issues with some things," she said after the hearing. "We've spent much too much time on this issue this year. I'm ready to put it on the table if they can't come to agreement in the next couple of hours. Today is the day."

Mayo has been lobbying for the right to allow the new Destination Medical Center authority to issue its own bonds for the project. Lenczewski, no fan of so-called "conduit bonding," balked. And Senate Taxes Chairman Rod Skoe, DFL-Clearbrook, agreed that the Destination Medical Center wasn't his top priority either.

"The Senate is working on more important issues," he said.

Mayo spokesman Karl Oestreich said by email that "discussions continue as part of the conference committee negotiations. We're confident that [Destination Medical Center] will be part of the final legislative package."

Rep. Kim Norton, DFL-Rochester, the original sponsor of the Destination Medical Center bill and a member of the tax conference committee, said Mayo's main concern was benefactors who wanted to get involved in the project, but didn't want to deal with the city. Mayo hoped that having the authority to do its own bonding would make it easier to bring in those outside benefactors.

"We do not want to turn away benefactors and investors from our community," Norton said. "If we close that door and they leave, we've hurt the whole project. I'm going to try to direct staff to narrow down what we're going

Lenczewski said Mayo has a few hours work it out before the Tax Committee signs off on a final version of the tax bill that doesn't include them.

"We're almost there," she said. "We can't let avarice get in the way."