WASHINGTON - The U.S. Forest Service plans to award more than $158 million in five-year contracts for new firefighting air tankers soon, according to an agency official.

The seven "Next Generation" large air tankers would supplement the aging, diminished fleet of eight aircraft currently in service, with the ultimate goal of phasing the older planes out altogether.

"We are moving ahead to modernize our fleet as part of our overall strategy to secure the best, safest air tankers available for fighting wildfires across the country in the years to come," Forest Service Chief Tom Tidwell said in a statement. "It is critical that we complete the 'Next Generation' air tanker contracting effort as quickly as possible as we face the prospect of another challenging wildfire season with a dwindling legacy air tanker fleet."

This is the latest step in a nearly year-long saga to get these new tankers into the air.

Last June, President Barack Obama signed a law to expedite the process to award these contracts, The Durango Herald previously reported.

Nine companies submitted proposals for seven tankers, and the Forest Service selected four companies in June.

But contractors' protests forced a do-over.

On Monday, the agency announced it had issued a "notice of intent" to award five-year contracts to five companies for seven tankers.

But the Forest Service can't immediately dole out the contracts. First there's a period where the companies involved can challenge the Forest Service's decisions.

And that's the period where the Forest Service first ran into problems last time around.

Forest Service Director of Fire and Aviation Management Tom Harbour said he couldn't speculate whether there would be protests again this year.

"We don't know," Harbour said in a telephone interview Monday. "We just don't know."

"We hope to get through this fairly quickly and hope to get these airplanes flying," he added.

The agency currently has eight large air tankers under exclusive-use contracts for 2013. In 2000, the Forest Service had 43 large air tankers available.

Sen. Mark Udall, D-Colo., has lobbied for these air tankers through legislation and a January letter to U.S. Department of Agriculture Secretary Tom Vilsack.

The Forest Service is part of the Department of Agriculture.

Udall's office sent out a strongly worded press release Monday imploring the companies not to protest the contracts, urging that they "put lives before legal disputes."

"I understand that the contractors have concerns about dollars and cents on these contracts, but Coloradans' lives and properties are on the line," Udall said in the statement."

"We've heard it could happen again," Udall spokesman Mike Saccone said of possible protests. "Another protest could set us back weeks, if not months."

The current fleet of air tankers is more than 50 years old, and half of the fleet will face mandatory retirement within a decade.

The agency's goal is to have these seven tankers in the air by the end of 2013, Harbour said. The overall objective is to have 18 to 28 large air tankers in service in the future.

"Our intention is to transition out of the old aircraft and into the new aircraft," Harbour said.

The Forest Service expects there to be fire problems in the southern half of Colorado in the upcoming wildfire season, Harbour said.

In 2012, six civilians died in wildfires in Colorado, according to Udall's January letter to the U.S. Department of Agriculture.

Nearly 400,000 acres burned and 648 structures were lost in the state because of wildfires, the letter said, including in the High Park and Waldo Canyon fires.

Frustrated by the shrunken federal air tanker fleet, a few Colorado state legislators attempted to create the state's own firefighting fleet.

Their Senate Bill 245 appeared to be on its way to passage Monday, but without the money to actually fund the fleet or hire pilots.

Instead, the bill creates an aerial firefighting division, whose first task will be to write a report on whether it makes sense for Colorado to buy its own planes. The report is due to the Legislature next April.

"When a partner brings strength into our partnership," Harbour said, "We're always happy."

Staff writer Joe Hanel contributed to this report from Denver.