The acting Liberal Democrat leader, Ed Davey, has claimed the "toxicity" of Jeremy Corbyn was a big factor in the Lib Dems' poor performance in last month's general election, saying voters backed the Tories rather than risk a "hard left" government.

Davey was defeated by Jo Swinson in last year's Lib Dem leadership contest and is expected to stand again after Swinson lost her East Dunbartonshire seat and resigned.

He conceded that his party "didn't fight a great election," but said the Lib Dems had also been hit by voters' fears about giving Corbyn's Labour the keys to Downing Street.

"In any election there are forces that you can control, and forces you can't control. And there's no doubt that the toxicity of Jeremy Corbyn to people who might have voted for us was greater than might have been expected," Davey said.

"You had liberals who were centrist but were very worried about a hard left government. This is what happened in 83 with Foot, in 92 with Kinnock," Davey said.

On the doorstep, he said, "we'd get: 'We really like you guys, we agree with you on "stop Brexit", but we've got to stop Jeremy Corbyn.' There's no doubt that was a big factor."

Davey conceded that his party's revoke message on Brexit had been poorly communicated and ended up alienating both leavers and remainers.

The Lib Dems said in their manifesto that they would revoke article 50 if they formed a majority government. "Communication was the problem, and that clearly didn't work with some people," Davey said. "It was particularly tricky for leave voters; but also, funnily enough, it annoyed remain voters too."

Davey said he would like to use that time to show that the Lib Dems were not a "one-trick pony" and had policies across a range of issues aside from Brexit.

"We have to be more than a one-trick pony, and we always have been, but we haven't always managed to get that over," he said.

In particular, he wants to highlight the need for better provision of care - an issue that affects him personally, as he has a 12-year-old disabled son.

"I want to lead a centre-left party who wants to see Britain be way more caring and progressive in how we reach out to people who need help. I want to change the culture and change the debate," he said.

"I now have a disabled son, who's 12, and one of the things I have learned from that, and from conversations with people, is one of the things you worry about is who is going to care for them when you're not there."

Asked whether he had a particular model in mind for funding an expansion of care provision, he said: "Clearly, how you pay for different kinds of care needs to be thought through. For some kinds of care, it's completely reasonable to ask the individual to make contributions, so I'm not suggesting it all goes on the state. However, there are a whole range of examples where you couldn't possibly expect people to make provision."

He used his first prime minister's questions as acting Lib Dem leader to challenge Boris Johnson over cuts to the financial support that bereaved families receive.

Davey said that in principle he would be prepared to join cross-party negotiations that Johnson has promised to set up to consider how best to fund social care for elderly people. But, despite reports suggesting the prime minister wants the committee up and running in his first 100 days, Davey said his party had not yet received an invitation.

As a former energy and climate change secretary, Davey said he would also be highlighting the need to take more urgent action to tackle the climate emergency in the next few months.

Other potential candidates to be the Lib Dems' fourth leader in three years include the party's education spokeswoman, Layla Moran, and the new MP Daisy Cooper.<iframe id="google_osd_static_frame_5924201395226" style="width: 0px; height: 0px; display: none;" name="google_osd_static_frame"></iframe><iframe id="obMntor" style="display: none;" src="https://widgets.outbrain.com/widgetMonitor/monitor.html?name=obm-cmp_fail&message=www.theguardian.com&stack=undefined&ver=1050112" name="obMntor"></iframe>