Billionaire Michael Bloomberg on Sunday walked back his long-time support for the controversial "stop and frisk" policing policy that disproportionately targeted black and Latino New Yorkers as he mulled jumping in the race for president."I was wrong, and I'm sorry," the former mayor of the US financial capital told a predominantly black megachurch in Brooklyn.The 77-year-old had long defended his backing of the aggressive technique, which gave the city's police broad powers to search anyone they suspected of criminality.READ | Who are the 2020 US Democratic presidential candidates?Bloomberg continued to back the programme - which is being phased out - even after a federal judge said in 2013 it violated constitutionally protected minority rights.The media tycoon's speech at the Christian Cultural Center in Brooklyn's deprived East New York neighbourhood appeared to be a tacit acknowledgement of the crucial minority backing he will need as he weighs a concerted challenge to US President Donald Trump in 2020.'Erosion of trust'READ | A year before 2020 election, a divided and 'angry' AmericaAt the 2011 peak of "stop and frisk" policing, 87% of some 685 000 stops targeted black or Latino people, according to the New York Civil Liberties Union.Around the same proportion of people stopped were cleared of wrongdoing.Citing the "erosion of trust" his stance had created among ethnic minorities, Bloomberg said: "I can't change history.""However, today I want you to know that I realise back then, I was wrong, and I'm sorry," he added.Bloomberg's words were met with a sceptical response as critics lambasted his reversal as vote pandering."He's right to apologise but voters should not fall for this," tweeted Kumar Rao, senior counsel at the Center for Popular Democracy."The apology was a decade late for those who were humiliated, harassed and intimidated by the government that is supposed to serve them," wrote New York Times opinion columnist Mara Gay."This Sunday, he finally asked black New Yorkers for their forgiveness. And their vote."'Bridge builder'Bloomberg has submitted paperwork in Arkansas and Alabama but has not announced his candidacy among a crowded field that includes another latecomer - former Massachusetts governor Deval Patrick.Patrick became the 18th candidate in the race on Thursday, less than three months before the first nomination votes are cast in Iowa.The 63-year-old former civil rights lawyer told NBC on Sunday he had considered announcing much earlier but held off when his wife of 35 years was diagnosed with uterine cancer."I think that I have a record of being a bridge builder," he said on talk show Meet the Press."I think that's pretty important at a time when not just the party in some respects but the nation is deeply divided."Patrick was one of the first African-American governors in the country, serving eight years in office. He is friends with party dignitaries including the last Democratic president, Barack Obama."We are in crisis in many respects here in America, and we used a crisis in Massachusetts to come out stronger economically, stronger socially and more fair," he added."I'd like to see if those experiences and that aptitude and that skill set can be offered in service to our nation."He broke with the majority of other Democratic candidates, however, when he declined to swear off taking donations from super PACs, political entities that can accept unlimited contributions by a single individual."I will have something to say about that (from a) policy point of view as we get a little further along," he said."But if there is going to be Super PAC money that supports me... the sources should be fully disclosed."