You don't have to look around too hard to realize that the "political swamp" in America stretches from sea to shining sea and from the highest offices in Washington D.C. to the lowliest of city halls on Main Streets all across the country.

The latest evidence of such comes to us from New York City where a Mayor Bill de Blasio donor-turned-felon testified in extraordinary detail yesterday that he and his businessman pals wrote the book on city corruption — buying off the Mayor’s Office and the Police Department using brazen pay-to-play tactics. As the New York Post details today, 34-year-old Jona Rechnitz went into staggering detail in his testimony about political favors he received from City Hall for a small $100,000 donation.

“We’re going to become significant contributors, but we want access,” Jona Rechnitz, 34, testified telling de Blasio fundraiser Ross Offinger after Hizzoner clinched the Democratic nod for mayor in 2013. De Blasio soon paid Rechnitz a visit in his office, the disgraced businessman told jurors in Manhattan federal court. De Blasio — who last year called his relationship with Rechnitz “not a particularly close’’ one — handed the wheeler-dealer his private cellphone number and email address, the witness said. The pair then began chatting “at least” once a week about “different issues in the city” — as Rechnitz funneled about $160,000 to de Blasio’s campaign and pet political projects, said the government witness.

Rechnitz appeared as the star witness in the bribery trial of former city corrections union chief Norman Seabrook. He is accused of bribing Seabrook to get him to invest $20 million in union pension money in a pal’s ailing hedge fund. But testimony quickly veered toward de Blasio, as Rechnitz was questioned about his ties to the ­administration.

Rechnitz said he had high hopes for the kinds of favors he could potentially receive.

“My mind was limitless,” he said. Business pal “Jeremy [Reichberg] had told me in the days of Giuliani, people made a fortune. “I was focused on making money, getting my name out there, becoming a big player in town. So I figured maybe I’ll buy an office building, and I’ll get the city as a tenant. Maybe I’ll need to get special permits to make residential developments.” Rechnitz and Borough Park businessman Reichberg initially targeted the NYPD in their pay-to-play scheme, doling out gifts and cash to cops in return for favors. Then they set their sights on City Hall, Rechnitz said. “We had the police going for us — and now it was time to get into politics,’’ he testified. Rechnitz started calling Offinger every time he needed a favor — including one involving a friend’s massive water bill and violations Rechnitz faced for a tenant subletting a residence on Airbnb.

Rechnitz even admitted to using "straw donors" to circumvent caps on individual political contributions, a scam which he says De Blasio's fundraisers were privy to.

In 2014, Rechnitz donated another $102,300 toward a failed effort led by de Blasio to help Democrats wrest control of the state Senate. Rechnitz said some of the dough was from straw donors, which is illegal. “A couple of people in my office, I had them write checks, because I wasn’t allowed to give more than $4,950. And I reimbursed them for those donations,’’ Rechnitz said. Rechnitz said he promised Offinger to hit target donations — and the fundraiser would stop by his office to check on the fundraising.

“I had a lot of pressure from him to bring that amount in,” Rechnitz said of the pledged amount.

But it wasn't just De Blasio's office where Rechnitz attempted to buy political favors as he admitted that his pay-to-play scams stretched north to the affluent suburbs of Westchester County and involved County Executive Rob Astorino.

During his hourlong testimony, Rechnitz said the corruption even extended beyond the Big Apple. Westchester County Executive Rob Astorino gave him and Reich­berg positions as police chaplains in exchange for their ­financial contributions — even though neither of them is a rabbi or a priest, Rechnitz said. “It meant that I got my parking placard,” said Rechnitz, whose firm JSR Capital donated $15,000 to ­Astorino’s campaign in June 2013. He said Astorino once approached him with a picture of a Rolex watch and asked for help in procuring it. “I told him I’m happy to give it to him; he doesn’t have to buy it,” Rechnitz testified. “He told me that he couldn’t take it as a gift. He had to pay something because that wouldn’t be allowed. It was a $7,000 to $10,000 watch, if I remember correctly.” In the end, Astorino agreed to pay $1,000 to $2,000 — and Rechnitz covered the rest, he said.

Not surprisingly, De Blasio's office dismissed Rechnitz' testimony saying "the administration has never and will never make government decisions based on campaign contributions"...clearly just more attempts to "criminalize behavior that is normal."