"Whether I'm going to be called, I don't know," Durbin said at a news conference. "But you know a subpoena is an order of the court to appear and if called to appear I'll appear."
Durbin's disclosure came a day after Blagojevich's lawyers asked a federal judge to issue a subpoena for Obama to testify and set off a media firestorm in the process when confidential information from the FBI's Blagojevich investigation became public.
In Washington, White House Press Secretary Robert Gibbs declined to say how Obama might respond to such a subpoena.
"I'm not going to comment on a pending criminal investigation," he said.
No court papers have suggested any wrongdoing on Obama's part.
Blagojevich is charged with scheming to sell or trade the Senate seat left vacant following the president's election in exchange for financial benefits for himself. He also is accused of illegally using his powers as governor to pressure potential campaign donors for contributions.
His brother, businessman Robert Blagojevich, is charged with helping him.
Both have pleaded not guilty. U.S. District Judge James B. Zagel has scheduled the trial to get under way June 3.
Durbin told reporters in Chicago that he received the subpoena about two weeks ago. One of Blagojevich's attorneys, Sheldon Sorosky, sounded uncertain when asked about the subpoena.
"If he says it, I guess we did," Sorosky said in a brief telephone interview.
Durbin had a well-publicized telephone conversation with Blagojevich shortly after the November 2008 election when politicians were starting to focus on who would get the Senate seat Obama was vacating.
By all accounts, they discussed a number of candidates.
"I had one conversation with this governor and I've reported it to you and everybody else over and over again," Durbin said at the news conference. "And if he or the government wants to call me in, I'll tell the same story."
Durbin spokesman Joe Shoemaker said: "Given the former governor's previous antics regarding this case, it's no surprise he is casting a wide net
- apparently from the president down to dogcatcher."