By Gram Slattery

WASHINGTON Republican presidential contender Nikki Haley's campaign is reserving $10 million in advertising, her camp said on Monday, as she tries to scoop up supporters of U.S. Senator Tim Scott, a fellow South Carolinian who dropped out on Sunday.

The ads will be placed on TV, radio and the internet starting in the first week of December in Iowa and New Hampshire, Haley's campaign said.

Those two states are the first and second, respectively, to select a preferred nominee to take on Democratic President Joe Biden in the 2024 general election.

Haley, a former U.S. ambassador to the United Nations, is in third place in the nominating contest behind former President Donald Trump and Florida Governor Ron DeSantis. Trump has been well ahead in opinion polls, with DeSantis a distant second.

Haley appeared to have caught a small break, however, when Scott unexpectedly dropped out on Sunday night. Both are South Carolina natives, and they have a similar base of donors and voters.

Two major donors to Scott's campaign told Reuters on Sunday night that had already switched their support to Haley, while a third said he would likely follow suit.

In a statement on Monday, Haley's campaign argued she was the best candidate to take on Trump, as she has been dedicating significant resources to Iowa, New Hampshire and South Carolina.

DeSantis, the only other Trump alternative with a significant national base of support, has been more focused on Iowa, where his team believes he has the best shot at a strong showing.

In state-level polls, Haley typically leads DeSantis in New Hampshire and South Carolina, while DeSantis leads Haley in Iowa.

Last week, DeSantis was endorsed by Iowa's governor, Kim Reynolds, who is deeply popular among conservatives in the state.

(Reporting by Gram Slattery; editing by Ross Colvin and Jonathan Oatis)