Theodore Roosevelt ran against Alton Parker in the presidential election of 1904. Roosevelt was the incumbent president, having taken over the presidency when William McKinley was assassinated.
Roosevelt was the unanimous nominee of the Republican Party in 1904. The democratic nominee, Alton Parker, was the Chief Judge of the New York Court of Appeals. Roosevelt won in a landslide, 336 electoral votes to 140.
Roosevelt left office in 1909, but he re-entered politics in 1912, when he again ran for president. He failed to gain the republican nomination, so he ran as the progressive nominee. He named his new political party the Bull Moose Party. He was unsuccessful in his bid for the presidency, in part because of an assassination attempt late in his campaign.