The phrase "by a close margin" is correct and is often used in written English.
You can use it when talking about a narrowly decided result or outcome, such as in a race or election. For example, you can say "The candidate won the election by a close margin of just a few hundred votes."
In a game that featured some intriguing individual matchups, the Mets lost each one by a close margin.
Torres predicts Chávez will win by a close margin, but is reluctant to say outright who he will vote for.
After all, Mr. Bloomberg spent a record-shattering $102 million to win a controversial third term by a close margin.
In the parliament most of my proposals on olive-oil reform were defeated by a close margin.
They have been carefully selected by matchmakers and promoters to perform as best they can and to lose, preferably by a close margin.
Democrats rushed to exploit the wounds in their ads, and Jimmy Carter won New York State by a close margin that fall, a pivotal loss for Mr. Ford.
"I'm very sorry that he lost the presidency by such a close margin.
"I'm very sorry that he lost the presidency by such a close margin," said Tom Giblin, chairman of the New Jersey Democratic Party.
While losing by such a close margin was disappointing to a Pioneer squad that had a program-best 15-3 record last season, it ultimately allowed Denver to surpass teams with better records in the tournament selection process.
LONDON — Prime Minister David Cameron survived a potentially humiliating challenge to his policies toward the European Union on Wednesday by a closer margin in Parliament than had been forecast, illuminating the depth of dissent within his party over an issue that has divided it for decades.
Since the Supreme Court decided to hear the case on Nov. 24, the results of the disputed Florida recount confirmed the election night tally, albeit by a closer margin, with Texas Gov. George W. Bush George W. Bush the winner of Florida's 25 electoral votes.
