Bomb blasts tore through two campaign events in northwestern Pakistan on Tuesday, killing at least 18 people, authorities said, as attacks ahead of Saturday’s national election continued against liberal politicians as well as a pro-Taliban Islamist party.

About 100 people have been killed since April in violence against candidates and party supporters, according to media tallies. Some experts say the election — a landmark democratic achievement that is expected to bring the transition of one elected government to another — has turned out to be the bloodiest in the country’s history.

The bombings this week also have sent a message that militants will spare no one involved in the democratic process, which they condemn as a violation of Islamic tenets. Victims now include supporters of a prominent right-wing cleric and parliamentarian, Fazlur Rehman, whose party has sought favor with extremists over the years but also joined coalitions with secular parties.

Rallies for candidates under the banner of Rehman’s Jamiat Ulema-e-Islam-F party were bombed on Monday and Tuesday, with a collective toll of more than 30 dead and scores more wounded. The Pakistani Taliban, which is fighting to topple the state, denied responsibility for Tuesday’s blast in Khyber Pakhtunkhwa province and said Monday’s attack in the Kurram tribal region was not aimed at Rehman’s party at large but an old foe who had only recently joined it.

The Pakistani Taliban has inexorably ratcheted up its attacks on politicians over the weeks and is now warning the public to stay away from the polls or risk death.

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“It’s obviously a new tactic,” said Peter Manikas, director of Asia programs for the National Democratic Institute for International Affairs, which has sent 44 poll watchers here. “It’s a different type of violence in trying to disrupt the election as a whole. It makes everything unsafe.”

The military says it will deploy 70,000 troops to protect polling stations, augmenting more than 500,000 police and security personnel.

“It’s pretty clear that this is the most violent election I have witnessed in 23 years” of monitoring votes in Pakistan, Manikas said.

The Taliban began its spate of attacks mainly against the pro-U.S. Awami National Party (ANP), dominant in Khyber Pakhtunkhwa, which borders the tribal belt, and the secular Muttahida Qaumi Movement (MQM), the dominant force in Karachi, the southern port metropolis.

Those parties had formed an alliance with the liberal Pakistan People’s Party (PPP), whose government just ended a full five-year term, an achievement never before seen in Pakistan’s turbulent 65-year history.

The accomplishment has stirred exuberant electioneering — every corner of the country seems to be plastered with placards bearing candidates’ faces — and defiant displays of national pride in the face of the violence.

On Tuesday, many Pakistanis, no matter their political allegiance, offered prayers for Imran Khan, the cricket hero turned populist party leader, following news that he had injured his head in a nasty spill from a forklift at a rally stage in Lahore. And they expressed relief when Khan’s campaign announced that the candidate’s injuries seemed minor and he was not in danger. The Associated Press reported that he had two hairline skull fractures.

Most Islamic scholars say Muslims have a religious duty to participate in the election. Among them is Samuil Haq, a cleric who heads his own faction of Jamiat Ulema-e-Islam and is often called the father of the Taliban because his madrassa schooled many of the movement’s leaders.

The PPP, ANP and MQM have scaled back but not stopped their quest for votes, despite clear dangers. On Tuesday, Zahir Shah, a PPP leader campaigning for his brother, a provincial assembly candidate, died when a roadside bomb was detonated by remote control near his vehicle in the Lower Dir section of Khyber Pakhtunkhwa. Five others, including two party supporters, also were killed, police said.

Earlier in the day, a suicide bomber on a motorcycle detonated his explosives near a vehicle carrying Mufti Syed Janan Khan, a provincial candidate with the Jamiat Ulema-e-Islam-F party. He survived the attack in the Hangu district, but 12 others died, police said.

Khan said he did not know who was behind the bombing. “It is premature to point the finger at someone,” he said. “I did not receive any threats from any quarter.”

In many recent attacks, the Pakistani Taliban has immediately asserted responsibility, but in other cases the perpetrators and their motivations may never be known.

The militancy is not monolithic, but is a fractured movement of many competing groups, including those with shifting alliances, said Ijaz Khattak, a professor at the University of Peshawar. He anticipates violence will continue unabated into Saturday.

“These elections are the bloodiest in Pakistan’s history,” Khattak said, “and they were expected to be.

“But people know that is the price one has to pay,” he added. “Democracy is the only viable way out of the mess Pakistan is in.”