A former pollster for former President Bill Clinton said on Monday that Democrats should accept that President Joe Biden is likely to become the party’s presidential nominee because replacing him at this juncture would be difficult. Biden declared he was staying in the race during a phone call into “Morning Joe” Monday morning where he dared his detractors to take him on during August’s Democratic Convention in Chicago. Mark Penn told “America Reports” co-host Sandra Smith that Biden had already secured the delegates necessary to earn the nomination, and that this would make it unlikely that h…