The Islamic State (IS) group is the prime suspect in the Ankara bombings that killed nearly 100 on Saturday, Turkish PM Ahmet Davutoglu has said.
No group has said it carried out the attack, but the government believes that two male suicide bombers caused the explosions.
The official death toll is 97, but one of the main groups at the march put the number of dead at 128.
The funerals of more of the victims are taking place on Monday.
Saturday's explosions ripped through a crowd of activists gathering outside the main railway station in the Turkish capital.
They were due to take part in a rally calling for an end to the violence between Turkish government forces and the militant Kurdistan Workers' Party (PKK).
Speaking on Turkish television, Mr Davutoglu said the bombings were an attempt to influence the forthcoming elections, due to take place on 1 November after a vote in June left no party able to form a government.
Many of the victims were activists of the pro-Kurdish HDP party, which says it is now considering cancelling all election rallies.
The HDP believes its delegation at the march was specifically targeted.
On Saturday the PKK unilaterally declared a ceasefire. However, this was rejected by the Turkish government, which carried out cross-border air strikes on PKK positions in southern Turkey and Iraq on Sunday.
Mr Davutoglu said authorities were close to identifying one of the suicide bombers.
Some local media have implicated the brother of a man who carried out an IS bombing in the southern border town of Suruc in July, which killed more than 30 people.
The BBC's Mark Lowen in Ankara says that critics of the Turkish government believe it is using IS as a scapegoat - and that murky elements of a so-called "deep state" are to blame for the bombings, aiming to shore up his support ahead of the elections.
The leader of the HDP, Selahattin Demirtas, said the state had attacked the people - and that the people of Turkey should be the recipients of international condolences, not President Recep Tayyip Erdogan.
Thousands of people attended the funeral of victim Uygar Cosgun on Monday, some of them chanting anti-government slogans, said the BBC's Middle East editor Jeremy Bowen.
One of the victims of Saturday's attacks has been identified as 70-year-old Meryem Bulut, a member of the Saturday Mothers group, who have protested about their missing sons since the 1990s.
Turkey is mourning the deaths of at least 97 people. These are just a few of those who lost their lives, clockwise from top left:
• Elif Kanlioglu: A 20-year old student in her second year of university, who loved studying foreign languages.
• Yilmaz Elmascan: Described by a friend as a peace-loving man, who got married last year. His wife is also said to have been killed in the attack.
• Sebnem Yurtman: Studied at Ankara university, and later in Adana. She was described as "full of life".
• Mesut Mak: He was a member of an agriculture and forestry union. He had a daughter.