Former Vice President Joe Biden entered the 2020 presidential race in late April, and even before his announcement he has led the Democratic field seeking to unseat President Trump.

Biden’s odds in March, before he formally announced his presidential bid, were pegged at 7/2, with Sen. Bernie Sanders of Vermont and Sen. Kamala Harris of California both at 4/1.

This week, oddsmakers have Biden at 5/1 odds, while Sanders has 7/1 odds. Harris has dropped to 12/1, according to Bet365.

Biden, 76, and Sanders, 77, are the oldest among the Democratic candidates. Trump, who is expected to win the Republican nomination, is 72 years old. Trump has 6/5 odds, which makes him the favorite, though he may not be the favorite once the Democrats have a nominee.

A potentially surprising showing to many may be the rise of South Bend, Indiana, Mayor Pete Buttigieg, 37, the first openly gay candidate, and the brunt of a presidential slight last week when Trump likened him to Alfred E. Neuman, a freckle-faced fictitious character that was the mascot of satirical MAD Magazine, who gained national prominence when he was offered as a write-in candidate for president in 1956.

Buttigieg’s odds are 16/1.

Despite a Time Magazine cover story touting her well-developed plans for corralling student loan debt, college tuition costs, and other economic issues plaguing the nation, Massachusetts Sen. Elizabeth Warren leads a list of dark horse candidates at 25/1.

Former Texas Rep. Robert “Beto” O’Rourke, 46, who previously held the fourth spot in March has fallen to sixth, despite successful fundraising and popularity among a younger base, also has 25/1. After O’Rourke, relative unknown Andrew Yang, 44, a New York entrepreneur who has proposed a Universal Basic Income plan, is also pegged at 25/1.

Warren, O'Rourke and Yang are followed by Sen. Cory Booker of New Jersey at 40/1. Booker came out strongly last week for a federal registry, safety courses, and background checks for gun owners to curb what he has called a uniquely American problem regarding mass gun violence.

More than 20 Democrats have announced candidacy for the nomination. The 2020 Iowa Democratic caucuses will take place on Feb. 3, 2020, while the New Hampshire Democratic primary is Feb. 11, 2020.