WASHINGTON (CNN) -- In the midst of a mushrooming controversy over the firings of eight U.S. attorneys, a CNN poll released Thursday shows that Americans are split over the future of embattled U.S. Attorney General Alberto Gonzales, with at least a quarter of the public unsure how they feel about him.

Gonzales has been criticized for his involvement in the firings, which some have said was for political gain. Overall, only 28 percent of Americans view him favorably, and a third have an unfavorable view.

But once again, the "don't know" category is fairly high. That's likely to change after Gonzales testifies before Congress on Thursday.

He is expected to face a grilling at the hands of the Senate Judiciary Committee during his testimony today regarding those firings. Some lawmakers are characterizing it a make-or-break session.

Going into the hearing, 38 percent of Americans say the attorney general should resign and 37 say he should not. The rest are unsure.

The poll of 1,218 adults was conducted April 10 - 12 by Opinion Research Corporation. The questions had a sampling error of plus or minus 3 to 4.5 percentage points.