“This is long from over,” Donald J. Trump, the former president and current felon, declared on Thursday, moments after a Manhattan jury convicted him on 34 counts of falsifying records to cover up a sex scandal.

Mr. Trump, the first American president to be branded a criminal, is banking on the jury not having the final word on his legal fate or his political fortunes. He will now appeal, both to a higher court and the American people, seeking to contain the fallout as he campaigns for the White House.

But even if the former — and possibly future — president persuades voters to toss his conviction aside, the appellate courts might not be so sympathetic.

Although Mr. Trump proclaimed at a news conference on Friday that he had plenty of ammunition to overturn what he called “this scam,” several legal experts cast doubt on his chances of success, and noted that the case could take years to snake through the courts.

And so, after a five-year investigation and a seven-week trial, Mr. Trump’s New York legal odyssey is only beginning, all but ensuring he will still be a felon when voters head to the polls in November.