Security is being stepped up in Turkey after a bomb attack left four dead days before a Nato summit of world leaders.
Mr Bush was due to be staying near the site of the Ankara blast
Police are said to be carrying out random checks in shopping centres, bus and train stations ahead of the talks.
The White House has said the attacks will not affect the schedule of US President George W Bush, who is among 50 leaders due to attend on Monday.
Istanbul's governor has identified the bomber, who died, as a 29-year-old woman with links to a hard-left group.
Two bombs exploded on Thursday, one in Ankara and another on an Istanbul bus where the four died and around 15 were injured.
Istanbul governor Muammer Guler said the bomb on the bus was being carried by Semiran Polat, 29, from the mainly Kurdish south-eastern province of Tunceli.
He said she was understood to have been wanted for activities within an "illegal leftist organisation".
"We know this organisation," he said. "We will make a statement once we
get confirmation of our investigation."
The device is believed to have exploded at the wrong time in the wrong place.
"It is understood that the target was neither the bus not the passengers aboard," Mr Guler said.
Turkish police have arrested three suspects, two men and a woman, who were believed to have been on board the bus when the explosion occurred, the state-run Anatolia news agency reported.
The device in Ankara exploded near the hotel where Mr Bush is due to stay on Saturday. Two people were injured.
A small radical Marxist group, MLFP-FESK, later said they placed a parcel bomb outside the Hilton Hotel, private NTV television reported.
No-one has admitted responsibility for the Istanbul attack.
Turkish police are expected to deploy more than 23,000 police in Istanbul for the summit and streets will be closed in area where Mr Bush will travel, say reports.
Security has been tight in Turkey in the run-up to the summit.
Dozens of suspected extremists have been held in police raids over the past few weeks, and about half a dozen small bombs have gone off in Istanbul in recent days, injuring several people.
Last month, the authorities claimed to have foiled a plot to bomb the Nato meeting after police arrested nine alleged members of radical Islamic group Ansar al Islam, believed to have links with al-Qaeda.
Fears of terrorist attacks have been running high in Turkey since November, when Istanbul was rocked by a series of deadly explosions.
Sixty-two people were killed and hundreds injured when two synagogues, the British consulate, and a branch of the HSBC bank were targeted by suicide bombers.