Liberals and conservatives in the next Congress are expected to push for "adjustments" in the consumer price index that could mean smaller cost-of-living adjustments in future for U.S. retirees and others whose pay, pensions or benefits are indexed to the nation's yardstick of inflation.

Currently federal and military retirees get COL raises every six months -- in March and September -- to help them keep pace with inflation. Social Security benefits for one of every six Americans are adjusted annually based on the CPI. Congress tried, and failed, this year to limit federal and military retirees to one COL per year. GOP presidential candidate Ronald Reagan pledged his support of the twice yearly COL system and the National Employees, largest of all federal-postal groups, says that nearly eight of every 10 members responded by voting for Reagan.

There is growing speculation that Congress, probably with the backing of the Reagan administration, will take action to change the CPI or to enact legislation that would limit retirees to a portion of the CPI rather than the full amount. The argument is that the CPI is inflated in the case of retirees, because it includes price rises for expenditures that retirees do not make.

Changing the CPI makes sense politically since an adjustment in it would almost automatically lower the rate of inflation -- mainly by using different measurements.

Based on current projections of the inflation rate, U.S. retirees could get a COL raise next March of around 4.4 percent. (That figure could be higher, or lower, depending on the actual increase in the CPI for the month of December.) That same projection shows retirees getting a raise in excess of 6 percent next September. (Again the exact amount will depend on the rate of inflation as measured by the CPI.)

Having experienced the political difficulties of trying to trim the number of raises that retirees get, Congress now is likely to push for a change in the CPI yardstick itself.