The state Republican committee recruited Keyes, a conservative radio talk show host from Maryland, to replace nominee Jack Ryan on the November ballot after Ryan withdrew in a sex scandal. Keyes has no ties to Illinois and rented an apartment in Chicago's suburbs this week.
Initial polling gives Democrat Barack Obama a 39 point lead. Both candidates are African-American. Keyes opposes abortion, affirmative action and the federal income tax.
"He represents the party that recruited him," Jackson told a conference call Thursday. "There are two parties and two candidates. Let's see which party is the most committed to supporting their guy."
Jackson said Bush challenged black Democrats to leverage their vote by supporting Republicans when he addressed the National Urban League in Detroit. He said the president now has the opportunity to campaign for a black Republican in Illinois.
"Mr. Keyes should be the standard-bearer for the Republican Party," he said. "It's a great opportunity for Republicans to show their commitment to expanding their base and competing for the vote."