WASHINGTON — One hundred years ago this month, a rotund right-hander, President William Howard Taft, started a baseball tradition by throwing out the ceremonial first pitch at the Washington season opener. On Monday, the Nationals turn to a svelte southpaw, President Obama, to make his Nationals Park debut.

For much of the past century, baseball was king in Washington, and presidents were on the throne, as Congress often recessed so members could attend what became known as the presidential opener. From Taft to Richard Nixon, every president made at least one opening-day toss in Washington. After a 33-year absence, baseball returned to Washington in 2005, and George W. Bush resumed the tradition by throwing the opening pitch for the Nationals.

This will be Obama's first Washington opener and his second time pitching as president. He did the honors at last year's All-Star Game in St. Louis and noted that he was allowed to practice his throw beforehand.

"I did not play organized baseball when I was a kid, and so, you know, I think some of these natural moves aren't so natural to me," Obama said.

The president has been warming up this time around, too, playing catch on the White House grounds to prepare for Monday's opener.

Obama's pitch last year wasn't the greatest. Cardinals first baseman Albert Pujols saved him from the embarrassment of a short hop by moving up to scoop the low pitch inches off the ground.

Taft got similar help from another Hall of Famer, pitcher Walter Johnson, as The Associated Press reported: "The throw was a little low, but the pitcher struck out his long arm and grabbed the ball before it hit the ground."

Monday's game will feature a rematch of the 1910 opener, Washington hosting Philadelphia, but not the same teams. The old Washington team — known as both the Nationals and the Senators — became the Minnesota Twins, and their 1910 opponent, the Philadelphia Athletics, now play in Oakland. Today's Nationals, who moved from Montreal, take on the Phillies.

In contrast with the choreographed presidential pitches of the modern era, Taft appeared a bit befuddled about what to do. After the umpire brought the ball over to him, "the president took the sphere in his gloved hand as though he were at a loss what to do with it," the AP reported.

Taft stayed for the entire game — something presidents rarely do these days — and the Nats blanked the Athletics, 3-0, behind Johnson's 1-hitter. The Washington Post gushed over the win, calling it "a sun-kissed, victory-blessed, roaring, rollicking, rousing opening day for the Nationals!"

The tradition has evolved over time.

In the beginning, the president threw the ball from the stands to the starting pitcher or even the umpire. Later, the president would toss the ball over a scrum of photographers into a crowd of players from both teams who would battle for the ball, which the president would autograph.

Nowadays, the nation's leaders take the mound and throw to the catcher or another player.

"It's hard to think of traditions that are a hundred years old, and to be able to participate in one, I think is something really special for our franchise, for our entire sport, and it's a real thrill to be involved in it," said Nationals president Stan Kasten.

President Franklin D. Roosevelt threw out a record eight Opening-Day pitches, including a 1940 toss that smashed into a newspaper photographer's camera.

"It was one of the worst that ever left a presidential arm, and that is saying something, for Hoover, Coolidge, Harding and Wilson have heaved some wild ones," the Post quipped.

In 1950, Harry Truman threw out two ceremonial pitches — one from each hand. A lefty, his right-handed toss didn't quite make the cut.

Later, it was the presidential autograph that was found lacking. In 1961, President John F. Kennedy's opening toss was retrieved by White Sox outfielder Jim Rivera, who demanded a more legible signature after JFK signed the ball.

"Do you think I can go into any tavern on Chicago's South Side and really say the president of the United States signed this baseball for me?" Rivera said, according to a report years later by Chicago Tribune writer David Condon. "I'd be run off."

A laughing Kennedy signed it again.