Without mergers, Delta Air Lines would still be a small regional carrier, one step removed from its crop-dusting past, the company's CEO said Wednesday.

Combining with other airlines through four past mergers has built the Atlanta company into the third-biggest airline in the world. Delta's proposal to combine with Northwest Airlines to create the world's largest airline is the next logical step, Chief Executive Richard Anderson said in an interview with other company executives in a meeting at The Atlanta Journal-Constitution.

And Northwest is the logical partner for Delta, Anderson said, because it has complementary routes, and the combined company would lead the industry in cash reserves. The merged companies would have an estimated $7 billion cash in reserves when the deal closes, which is expected at year's end.

Ed Bastian, Delta president and chief financial officer, said cash is Delta's best weapon as it combats a looming recession and record fuel costs. Delta's fuel bill is expected to be more than $6 billion this year, compared to $4.7 billion last year.

The planned merger also will save money, Bastian said, by generating an estimated $1 billion in additional revenues or cost savings.

The executives, on their second day of a road show aimed at selling the merger to regulators, shareholders, employees and politicians, painted the merger as a nearly essential step in 78-year-old Delta's continued transformation.

Anderson said the airline, which started as a crop-dusting service in Macon, cannot grow organically because air space, gate slots and market opportunities are limited. Combining with Northwest would give Delta access to Asian routes it could not capture otherwise, he said.

The $17.7 billion, all-stock deal, announced Monday, would create an airline with about $35 billion in revenues, more than 800 jets and routes stretching from Dubai to Bangkok.

"We want to be the strongest and most well-positioned globally," Anderson said. "I would say Delta wouldn't be here today if it hadn't been for four big mergers."

Delta snapped up Chicago and Southern in 1953; Northeastern in 1972; Western in 1987; and Pan Am in 1991.

Several marquee airlines have disappeared since the industry was deregulated in 1978, Anderson noted. The airlines that have survived, he said, are the ones that grew through mergers.

Anderson and the other executives said they are confident they can avoid the pitfalls that have tripped up other airline mergers. Historically, airline mergers have been hobbled by unexpected costs, problems with integrating computer and other systems, and combining sometimes hostile work forces.

"It's always a leadership challenge to put two big companies together," said Anderson, who sat at the deal-making table in past positions at Continental and Northwest, where he was CEO from 2001 to 2004. Still, the Delta executives said, they expect many employees at both companies to

ultimately support the merger.

The pilots union for Eagan, Minn.-based Northwest opposes the merger. It is the only group at either carrier that hasn't been promised an equity stake, pay raises or other perks as a result of the deal.

Delta reached a tentative agreement last week with Delta's pilots, giving them a 3.5 percent equity stake in the combined companies and additional pay raises in exchange for contract amendments that gives the company more flexibility during the merger process.

Anderson and Bastian said they still hope to bring Northwest's pilots on board before they complete their merger sometime later this year. Doing so would make integrating the two pilot groups much easier. US Airways and AmericaWest did not get such agreements from their pilots before merging

in 2005; their pilots still work under separate seniority lists and contracts, complicating operational integration.

"I'm confident we can still get this done together," Bastian said.

The merger must still be approved by shareholders of both airlines and federal regulators, a process that could take months.

Some politicians are already vowing to fight the Delta-Northwest deal. Rep. James Oberstar, the Minnesota Democrat who heads the powerful House Transportation Committee, has called it "the worst development in aviation history."

Anderson said he was confident the merger will win approval from federal regulators because the two airlines don't have overlapping routes, key to sidestepping anti-trust issues.

"I think we've just got to go through the process," he said.

The merger didn't appear to woo Wall Street. After plunging Tuesday, shares in both companies fell again Wednesday. Delta dropped nearly 6 percent to $8.62 per share, and Northwest dropped 7 percent to $9.55.

Credit rating firm Moody's said Wednesday that it will review debt ratings of Delta and Northwest for possible downgrades.

Both Anderson and Bastian said they were not concerned about Delta's and Northwest's stock performance following the merger announcement.

"The price of fuel set an awful backdrop to announce a merger," said Bastian. Jet fuel prices hit a record high $3.48 a gallon Tuesday, just as the merger news hit the market.

A penny increase in jet fuel adds $25 million to Delta's annual fuel bill.

Both men said they think speculators bailed out of both stocks after the merger was announced. The stocks traded about four times their normal volume Tuesday, the first trading day after the merger was announced.

"When we talk to the people who own a lot of shares, they are fully supportive," Anderson said. "The people who own millions of shares, these people are pleased."