June 24 (Reuters) - Delta Air Lines Inc's CEO is expected to support the U.S. Export-Import Bank's assistance for sales of Boeing Co's widebody jets, softening his stance at a time when critics are mounting pressure to wind down the agency, the Wall Street Journal reported.

Delta Airlines has long argued that Ex-Im Bank financing allows foreign competitors to buy Boeing planes on better credit terms than it can obtain.

Delta's chief executive, Richard Anderson, plans to use a speech at the Aero Club in Washington, D.C. on Tuesday to distance the company from the calls of some Republicans and small-government advocates for the bank to be wound down, the Journal said. (Delta Chief Softens Stance on Ex-Im Bank Support for Boeing Big-Jet Sales - WSJ)

According to a draft of the speech obtained by the Journal, Anderson is expected to propose that the bank continue supporting sales of Boeing widebody jets to a limited number of airlines that lack alternative finance options, at least for as long as rival Airbus Group NV enjoys similar backing from European export-credit agencies.

There is a heightened scrutiny of the Ex-Im Bank as U.S. lawmakers debate whether to reauthorize the 80-year-old agency. The newly elected No. 2 Republican in the House of Representatives said on Sunday he opposed renewing its charter.

Anderson is expected to emphasize in his speech that he doesn't want Ex-Im to shut down, arguing that the bank has a vital role in preserving U.S. manufacturing jobs, the daily reported.

The Export-Import Bank backed $37.4 billion in exports in 2013. Scrapping the bank would be a blow to Boeing, Caterpillar , General Electric and other U.S. companies that rely on Ex-Im financing to make sales in export markets where commercial lending is scarce.

Delta Air Lines representatives could not be immediately reached for comment outside regular U.S. business hours.