He was convicted on charges of stemming from special counsel Robert Mueller's investigation into Russian collusion in the 2016 presidential election.
According to the top US daily, Lewandowski was seen as someone having hostile relationship with members of the national press.
Manafort, who had once lobbied for pro-Inter-Services Intelligence and anti-India groups, had been recently attracting negative publicity for his alleged lobbying activities in Ukraine.
The Clinton campaign and the Democratic Party have alleged that the Russian interference had contributed in Trump's electoral victory
Trump's former campaign manager Paul Manafort was on Monday charged with conspiracy against the US.
The extraordinary admission on Tuesday came the same day as Trump's former campaign chairman, Paul Manafort, was convicted of five counts of tax fraud, two counts of bank fraud and one count of failure to disclose a foreign bank account. The jury was unable to reach a verdict on the remaining 10 counts, and the judge declared a mistrial on those charges.
Trump's views run contrary to the Obama administration, which had imposed economic sanctions against Russia.
Sleuths of security forces and secret service agents have converged on the city and huge make-shift iron walls have come up several blocks around the convention's location.
Hours before the party's convention, Chairwoman of the Democratic party Debbie Wasserman Schultz resigned.
Critics said parts of her speech were lifted verbatim from remarks First Lady Michelle Obama made in 2008
Flynn appeared before a federal court on Friday morning to plead guilty after ex-FBI director Robert Mueller, who is investigating allegations of Russian interference in the presidential election as a special counsel, announced that Flynn was charged with "wilfully and knowingly" making "false, fictitious and fraudulent statements" to the Federal Bureau of Investigation about his conversations with Russia's then ambassador to the US Sergey Kislyak.
'The facts have become unimportant and useless.' 'What is important is the constantly shouting of patriotism even as one undermines the interests of the people.' 'And the abusing of rivals as being traitors,' says Aakar Patel.
"My son is a high-quality person and I applaud his transparency," Trump said.