Democrats made a last-ditch attempt Thursday to create three new all-urban congressional districts along the Wasatch Front surrounded by a vast doughnut-shaped rural one — but Republicans on the Legislature’s Redistricting Committee torpedoed that on a straight party-line vote.

Instead, the committee gave its final approval to a "pizza slice" plan that cuts Salt Lake County three ways and attaches two of the pieces to large rural areas and ties the other to relatively rural western and southern Utah County.

Democrats say that will dilute their votes in their one stronghold in Salt Lake County, and increase chances that the GOP will win all four of the state’s congressional seats. Republicans say it will ensure that all Utah members of Congress will represent both rural and urban issues.

"We will sue if it is unchanged," by the full Legislature in a special session next week, said Utah Democratic Party Chairman Jim Dabakis. "It’s manipulative. It’s awful."

Also, a parade of citizen and reform groups criticized that "pizza slice" plan at the committee’s final meeting saying it is too political, would make Salt Lake County slices the minority parts of their congressional districts, and would divide such cities as Holladay into three pieces.

Rep. Ken Sumsion, R-American Fork, House chairman of the committee, said whether more changes come when the full Legislature considers it next week "depends on the governor," but would not elaborate, hinting that Gov. Gary Herbert wants changes.

Some committee members have said privately that Herbert is pushing for changes that might help convince Rep. Jim Matheson, D-Utah, to run for reelection in the U.S. House instead of challenging him for governor. Allyson Isom, spokeswoman for Herbert, said such inferences by members are incorrect, and that Herbert simply wants a plan that is fair for all.

Amid all that, the pizza-slice plan was approved by all of the committee’s 14 Republicans and opposed by its five Democrats.

Senate President Michael Waddoups seemed to take umbrage that committee Democrats tried to create three congressional districts entirely in Salt Lake, Davis, Utah and Weber counties surrounded by the large doughnut rural district.

Waddoups noted that the Democratic plan would divide Salt Lake City, and complained that Democrats and others had told him that keeping that city whole was a priority — so he had fought to do that in the "pizza slice" plan. He said he now releases Republicans who had been loyal to his request for that, and said Republicans may look at splitting the city now in other pizza-slice plans.

Sen. Ben McAdams, D-Salt Lake City, called that "feigned" indignation. He said while Republicans keep Salt Lake City whole, they do it in a way that makes it a minority population in a district that stretches through most of southern Utah and divides communities of interest.

Sen. Gene Davis, D-Salt Lake City, said the Democratic plan recognizes that "Utah is the seventh-most urbanized state in the nation," and the Wasatch Front has 75 percent of the state’s population and should have three of four districts. "We need to respect that [urban] population."

Rep. Brian King, D-Salt Lake City, said GOP plans to create districts to help protect rural interests would be "allowing the population tail in Utah to wag the dog."

But Rep. Don Ipson, R-St. George, said the vast "doughnut" district that Democrats proposed to surround the Wasatch Front would be "a logistical nightmare. It would be physically impossible for anyone to cover that kind of geography" as a representative.

Instead of voting directly on the Democratic proposal, Republicans made a substitute motion to vote on their pizza-slice plan instead, and passed it. But first, citizen and reform groups took some shots at it.

David Irvine, representing the Utah Citizens Counsel, a group led by such people as former GOP Gov. Olene Walker and former University of Utah President Chase Peterson, said Salt Lake County should not be divided in any more than two districts to keep common interests together.