Combined car bomb and suicide attacks in the Somali city of Baidoa that killed at least 30 people at the weekend appear to be part of an accelerating offensive by al-Shabaab. The group aims to disrupt national elections planned for this year, undermine public confidence in international peacekeepers and bring down Somalia’s weak western-backed federal government.

The Baidoa attacks targeted a busy restaurant where patrons were watching the English Premier League football match between Manchester United and Arsenal on Sunday. The bombings, claimed by the al-Qaida-affiliate, followed a lethal attack in the capital, Mogadishu, on Friday. An al-Shabaab spokesman said government officials had been targeted, but most of the dead in both incidents were civilians.

Somalia has suffered two decades of lawlessness, insurrection and invasion since the collapse of the Siad Barre dictatorship in 1991, earning it the label of “failed state”. Instability has spread to neighbouring Kenya, home to large numbers of Somali refugees, following Nairobi’s decision in 2011 to intervene militarily.

Enraged by Kenya’s support for the African Union’s 22,000-strong peacekeeping mission in Somalia (Amisom), al-Shabaab caused mass casualties in attacks on a university in Garissa last year and at the Westgate shopping mall in Nairobi in 2013. Last month as many as 200 Kenyan soldiers died in an al-Shabaab attack on a military camp inside Somalia, according to Somalia’s president, Hassan Sheikh Mohamud.

Kenyan authorities disputed the figure but did not give a specific death toll. Al-Shabaab later distributed photos of dozens of dead Kenyan soldiers, many apparently shot in the head.

“We have been winning for years and months but [in] that El Ade battle [at the Kenyan camp], we were defeated,” Mohamud said.

The relative success of Amisom, which is backed by the UN and western countries, in regaining control of Somalia’s main cities since 2011 has encouraged hopes of a lasting national recovery. But the security situation is deteriorating again as the jihadis, who control large swaths of rural south and central Somalia, battle to demonstrate they are still a force to be reckoned with. Last autumn Britain said it was sending special forces to assist Amisom.

The Islamists also oppose what they see as a foreign-imposed electoral process, which was finally agreed last month. The planned election this year will create a new two-chamber parliament in which women will hold nearly a third of seats.

Despite enthusiastic backing from Ban Ki-moon, the UN secretary-general, who called the election plan “a roadmap towards universal suffrage by 2020”, it has faced strong criticism from opposition politicians because MPs will not be directly elected. A power-sharing formula agreed by rival clans will be used instead. In 2012, a group of 135 elders picked the president. Opponents say this is all a plot to keep the current government in power.

Mohamud said in an interview with Foreign Policy magazine last year that poor or non-existent security prevented the immediate introduction of a nationwide one-person, one-vote ballot in 2016. But security was not the main reason.

“There is a much bigger and wider concern I have for the election. We don’t want [it] to create new conflict, new division, within the society, which is the experience of many post-conflict environments. We don’t want elections to create winners and losers … This time around, Somalia is still fragile,” Mohamud said.

Critics say such a circumscribed electoral process is not the answer. “Anyone who says elections are impossible is listening to people who want the status quo maintained,” said the former prime minister Abdiweli Sheikh Ahmed. “The international community is not serious about this.”

Islamist terror and political divisions are not the only threats to Somalia’s rehabilitation. To the dismay of African leaders, the EU has cut funding for Amisom by 20%, despite Brussels’ recent emphasis on reducing refugee flows and migration into Europe by stabilising conflict areas in Africa and the Middle East.

Uhuru Kenyatta, Kenya’s president, said Amisom needed more international support, not less. “Whereas the continent is footing the bill of stabilising Somalia by blood and flesh, it is disheartening that the international community is even contemplating to reduce support,” he said.

The EU and UN are the main donors to Amisom. Troop-contributing governments have received €1.08bn (£780m) in stipends and allowances from the EU African Peace Facility (APF) since 2007. Amisom currently accounts for more than 85% of total APF resources.

The EU commission says the cuts are necessary because money is needed for other African peace missions and to respond to new crises that may arise in future.