The Conservative Party must change quickly or “die”, the party’s leader in the Senedd has said.
Andrew RT Davies added that colleagues should apologise for not keeping immigration promises.
Mr Davies will address the Birmingham conference on Sunday, the first gathering of Tory politicians and activists since July’s election defeat.
The party lost power at Westminster and was reduced to 121 MPs.
The Conservatives were wiped out in Wales.
As well as failings on immigration, voters were turned off by the party’s “dogmatic” stance on the economy, Mr Davies said.
He said there needed to be a “zero tolerance” approach to immigration, with those in the UK illegally removed swiftly.
Mr Davies said: “The Conservative Party must change. No party has a God-given right to govern. We failed to keep our promises and we must say sorry.
“By proudly reflecting our conservative values, we will persuade them [voters] to back the Welsh Conservatives.
“But we must also change how we are perceived on the economy. We must be seen as pragmatists, not ideologues.”
Mr Davies believed his party’s take on things like nationalisation must change.
“Welsh industries and communities have paid the price of globalisation and our party must do more to protect them,” he said.
“We must show that we care, and defend their sense of community, togetherness, and local pride.
“If our party changes, we’ll recover quickly, and we’ll succeed in 2026 and 2029.
“But if we don’t, we’ll die. That’s the choice.”
The Labour Welsh government was dominated by an “extreme metropolitan worldview, combined with soft nationalism,” he added.
This, he believed, had led to 20mph speed limits and the expansion of the Senedd rather than improving public services.