In response to T. R. Reid's critical commentary of Gov. Evan Mecham {June 21}, please note the following list of factual errors and their corrections:

Statement: "Mecham's rocky start could stunt the growth of the flourishing Arizona Republican Party."

Correction: From January to March 1987, the Republican Party increased its lead over Democrats in Arizona by 10 percent.

Statement: ". . . Democrats handed Mecham the governorship on a platter. . . . Sure enough, Warner and Schulz split the Democratic vote and Mecham won. . . ."

Correction: Carolyn Warner and Bill Schulz split the Democratic vote, but Gov. Mecham and Mr. Schulz split the Republican vote. A CBS exit poll showed Gov. Mecham would have won by a larger margin (55 percent to 45 percent) if Mr. Schulz had not been in the race. In addition, two other studies, one by Mrs. Warner's own campaign manager, showed Gov. Mecham would have won even without Mr. Schulz in the race.

Statement: ". . . he vowed to kill a 1 percent state sales tax, calling its backers 'liars'."

Correction: He called the tax the "liars' tax," not the backers of it. The main proponent of the tax, when asked how come the tax became permanent after promising it would be only temporary said, "I lied."

Statement: "Three months after taking office, he announced that he would keep the tax until mid-1988 at least."

Correction: In his State of the State message and in his recommended budget for 1987-88, Gov. Mecham proposed a repeal of the once-temporary sales tax. The legislature howled in protest. The governor then recommended a phase-out of the tax. Again more howls from the legislature. Finally, the governor said, "If I show you how that money can be saved through better management, will you consider repealing the tax in 1988-89 or with a phase-out approach?" The answer was a begrudging "Yes." Gov. Mecham is now working on a "War on Waste" to prove to the legislature the 1 percent tax is not needed.

Statement: "Mecham can brush off such attacks as the predictable response of an elite 'establishment' when an outsider comes to power. It is harder for him to belittle or ignore the steady beat of ridicule from the general public."

Correction: If Mr. Reid had taken the time to speak to supporters or, better yet, listen to one of the governor's twice-monthly, one-hour, state-wide radio broadcasts, he would see that Gov. Mecham has a great deal of support throughout the state. That support is there in spite of the inaccurate reporting of the press and the vociferous attacks from the opposition.

RONALD J. BELLUS Press Secretary, Office of the Governor Phoenix