A “trial balloon” is a preliminary announcement for a possible campaign, appointment, or other political action.
Floating a trial balloon means testing public opinion to see whether a project is likely to succeed. This is often done through the media, by deliberately leaking news to reporters and then gauging public reaction to the news.
If public response to the trial balloon is positive, then the politicians in question are likely to follow through with the idea. If public response is negative, then politicians can easily back down from the proposal, since it was never declared officially.
The expression “trial balloon” is a direct translation from the French phrase, ballon d’essai. The French phrase was popularized in the early 19th century, when adventurers were trying out hot air balloons.
As a safety precaution, balloonists sent up a small, unmanned balloon to test the direction of air currents before taking off on a manned flight.
Over time, people started to use the phrase “trial balloon” figuratively as well. In English, the expression was first used in the figurative sense in 1826.
Trial balloons allow politicians to test out even the most improbable ideas. In 2010, some of Hillary Clinton’s supporters floated a trial balloon to see whether Ms. Clinton could ever serve on the Supreme Court. But the White House quashed those rumors almost as soon as they started to spread.
Politico summed it up neatly:
The White House on Monday hurriedly punctured the trial balloon that had Secretary of State Hillary Clinton heading to the Supreme Court and, in the process, dealt another blow to the fading American tradition of appointing prominent public figures to the court.
Trial balloons can backfire, at times. Politicians who are overly-reliant on trial balloons can seem to be weak or indecisive. It’s similar to politicians who rely heavily on opinion polling to guide their moves.
That’s what David Ignatius thought of President Obama, anyway. Writing in the Washington Post, Ignatius grumbled that Obama was relying on a trial balloon to decide whether Larry Summers would make a good chair of the Federal Reserve. Ignatius wrote:
Obama has an unfortunate history of this kind of government by trial balloon. He floated Susan Rice as a potential secretary of state until the attacks on her became so intense that she withdrew. She’s now national security adviser, but scarred. Then the White House surfaced Chuck Hagel for secretary of defense. He was confirmed, barely, but was perhaps irreparably damaged in the process.
In 2017, Ruth Ben-Ghiat took this complaint one step further. Writing for CNN, she wrote that President Donald Trump was using trial balloons to test out extremist ideas and gradually get the public used to the kinds of idea that would normally be shocking:
Trump has used speeches and tweets to launch trial balloons for almost two years now, and in the process has changed our expectations for what a leader of a democracy might say and do.