By Jessica Frank-Keyes The Conservatives need to win back voters who have gone “on strike” over the failure to tackle immigration and extremism, Robert Jenrick has said. The former immigration minister argued the Tories under Prime Minister Rishi Sunak need to admit to their “mistakes” in a bid to reclaim their voting base ahead of the general election. It came after the party suffered a drubbing in the local elections last week, losing nearly 500 council seats, the Blackpool South by-election and the West Midlands mayoralty. Jenrick, speaking at the launch event for a paper on curbing net mig…