Vice President Kamala Harris has made marginal gains or held steady in betting odds on the 2024 Presidential election.

The action, which U.S. bookmakers cannot legally take, has stayed in Harris' favor after the race's first debate between the Vice President and former President Donald Trump.

Post-debate polling echoes the narrow lead for Harris at the betting window as a USA TODAY/Suffolk University poll taken after the debate showed Harris up 49%-46% in the critical battleground state of Pennsylvania.

Harris expanded her lead at the three offshore betting houses USA TODAY regularly surveys and remained at -125 to even money at U.K. bookmaker Bet365.

The Democratic swing comes as Trump deserted the possibility of further debates against Harris after the decisive loss in Philadelphia.

Presidential betting odds timeline

Presidential betting odds as of 9/23

Bet 365

Kamala Harris: -125

Donald Trump: EVEN

via Covers.com

Bovada

Kamala Harris: -130

Donald Trump: +110

BetOnline

Kamala Harris: -130

Donald Trump: +110

Oddschecker

Kamala Harris: -114

Donald Trump: +122

How has this race compared to previous elections?

Harris held the narrowest lead over Trump of any recent Democratic nominee at both the 50 and 75 days-until-election landmark.

Harris stood at -110 to Trump's +116 at U.K. bookmaker Betfair Exchange when the clock ticked under 50 days. Biden stood at -116 at the 50-day mark in 2020, though Trump had longer odds at +132.

The odds at the 50-day mark for the past three elections were:

2024

Harris: -110

Trump: +116

2020

Biden: -116

Trump: +132

2016

Clinton: -182

Trump: +210

Harris' spread at the 75-days-to-election mark was narrower compared to the previous Democratic challengers. Then-Secretary of State Hillary Clinton held a wide -323 to +370 margin over Trump at Betfair. Trump won the 2016 race, though he lost the popular vote, marking the second time a betting underdog won the White House.

The odds for the last three elections at the 75-day mark were:

2024

Harris: -102

Trump: +110

2020

Biden: -132

Trump: +144

2016