2024 presidential election odds: How betting lines stack up versus previous debates

Betting odds narrowly favor former President Donald Trump over Vice President Kamala Harris as the candidates head into the first debate between each other at the National Constitution Center in Philadelphia Tuesday night.

Trump retook the betting lead this week, pulling ahead for the first time since mid-August. The action, which U.S. oddsmakers cannot take part in legally, moved definitively toward the vice president during the Harris-Walz ticket's honeymoon.

Harris held the narrowest lead over Trump of any recent Democratic nominee at the 75-day mark, sitting at -102 at U.K. oddsmaker Betfair Exchange.

Trump leads at Betfair, standing at -108 to Harris' +114 as of early Tuesday morning.

Considering how much the first 2024 presidential debate swung fortunes after President Joe Biden's much-maligned performance, odds could swing when Harris and Trump take the stage Tuesday night.

Harris-Trump presidential debate: Follow here for live updates

Where did previous races stand at the first debate?

Trump-Biden 2024

Going into what proved to be a disastrous debate for Biden, Trump was favored at Betfair with -130 odds, compared to +200 for Biden. The day following the debate Biden's odd ballooned to +420.

Biden-Trump 2020

Betting houses had Biden ahead before the first time the pair squared off in 2020. Biden stood at -127 to Trump's +132 before the debate. After the debate Biden extended his lead to -141 to Trump's +148.

Presidential betting odds timeline

Note: Zero denotes even odds.

Presidential betting odds as of early Tuesday, Sept. 10

Bet 365

  • Donald Trump: -138

  • Kamala Harris: +110

via Covers.com

Bovada

  • Donald Trump: -115

  • Kamala Harris: -105

BetOnline

  • Donald Trump: -125

  • Kamala Harris: +105

Oddschecker

  • Donald Trump: -110

  • Kamala Harris: +118

How accurate have election odds been in past presidential elections?

The betting favorite has only lost twice since 1866, according to the Conversation, a nonprofit news organization.

Hillary Clinton's odds stood at -323 at the 75 day mark, but Clinton went on to lose the election in one of the two times the betting underdog won on election night.

The other upset came in 1948, when Harry Truman (D) beat eight-to-one odds to defeat Thomas Dewey (R).

How to watch the Presidential debate

On Tuesday, Sept. 10, at 9 p.m. EDT, USA TODAY Network will stream The ABC News Presidential Debate Simulcast on the USA TODAY channel, available on most smart televisions and devices.

This article originally appeared on USA TODAY: Presidential election betting odds: Pre-debate lines for Harris, Trump