WASHINGTON — Former Representative Beto O’Rourke said Monday he “can do a better job” of communicating his 2020 campaign message, acknowledging that he must take steps to revive his once-promising presidential bid after seeing his polling dip in recent weeks.

Appearing on Rachel Maddow’s MSNBC show, Mr. O’Rourke said that after two months in the race, and “more than 150 town halls,” he recognized he had to broaden his strategy to appeal to a national audience and not only the voters and news media at his events.

“I have an opportunity to answer your questions, Rachel, and address those who may not have been able to attend them and make sure that they can hear what this campaign is about and how I answer the questions that are put to me,” he said. “So I hope that I’m continuing to do better over time.”

It was a striking concession from Mr. O’Rourke, whose surprisingly strong challenge against Senator Ted Cruz of Texas last year vaulted him into national prominence and won him high expectations when he entered the presidential race.