DES MOINES — Lawmakers finalized a $6.244 billion state budget and a major mental health system redesign Wednesday, but adjourned without passing a comprehensive property tax relief package — a top priority they promised to continue working on during the interim and to fight about as they hit the 2012 campaign trail.

The 84th General Assembly’s second yearly meeting ended on the 122th day — 22 days beyond the adjournment target — after the Senate adjourned at 5:23 p.m. and the House followed suit 50 minutes later.

Lawmakers from both political parties pointed to initial steps they took to reform the state’s education system and shift to a more-equitable regional approach of providing uniform mental health services locally as major accomplishments. But they conceded it was a major disappointment to adjourn without having provided promised tax relief to businesses by lowering rates on commercial and industrial property — an issue that has gone unresolved for 34 years.

Also, the Senate adjourned without taking up a bill that would have established a regulatory and rate-making structure for MidAmerican Energy’s proposal to build a nuclear energy plant using modular technology sometime in the future. Senators also did not join the House in approving a resolution nullifying a Natural Resources Commission rule banning the use of lead shot when hunting mourning doves when the season opens Sept. 1.

Leaders of the House and Senate met with Gov. Terry Branstad during the afternoon in hopes of finding compromise on a plan to reduce commercial property taxes while limiting growth for other property classes and providing state “backfill” money to cushion the potential loss of revenue to local governments. However, those talks failed to resolve an issue that the governor and both Republicans and Democrats in the split-control Legislature had identified as their top priority for the 2012 session.

“The only option is if the governor wants to call a special session,” said Sen. Brad Zaun, R-Urbandale, minority whip of the Senate GOP caucus.

Senate Majority Leader Mike Gronstal, D-Council Bluffs, said the property tax negotiations got caught up in partisan politics and resulted in lawmakers walking away from a proposal that left $350 million in potential property tax relief “on the table.”

“It’s a tough issue, but I want you to know we offered compromise,” Gronstal said.

House Speaker Kraig Paulsen, R-Hiawatha, said it was “regrettable” that majority House Republicans and majority Senate Democrats couldn’t come together on an agreement to cut business taxes — noting House members sent four proposals to the Senate over two sessions. He pledged to continue to seek common ground during the interim and pledged that Republicans would be back next year with a proposal to cut Iowans’ taxes by $390 million — using the $90 million in a new taxpayer trust account and the state’s projected $300 million ending balance.

Branstad thanked lawmakers for considering his administration’s priorities and for adopting a significant number of them.

“However, the 2012 session may be remembered as much for what failed to be accomplished as for what actually was accomplished,” the governor said in a statement. “Despite the best efforts of my office and a bipartisan majority in the Iowa House, the inability of Senate Democrats to adopt serious property tax reform has put Iowa taxpayers in jeopardy of seeing significant property tax increases in the coming year.”

Gronstal refuted that claim, saying “I gave and I gave and I gave, and as far as I can tell I was the only one negotiating and I think in the end they decided let’s play politics with this issue. How can you walk away from an offer of a 25 percent reduction in commercial property taxes of $350 million? You walk away for one reason — you want to play politics.”