The temperature is rising in the battle to lead Senate Republicans, with Sens. John Thune (S.D.) and John Cornyn (Texas) facing a one-week sprint to win the top spot after the GOP clinched control of the upper chamber.

According to multiple senators and aides, Thune and Cornyn, along with their allies, have been burning up the phones of members in search of support ahead of next week’s election to replace outgoing Senate GOP Leader Mitch McConnell (Ky.).

Thune, the Senate GOP whip, has been considered a slight favorite to replace the Kentucky Republican. He is the top vote counter on the GOP side and has proven an able fundraiser and campaigner.

But few are counting out Cornyn, a former whip and top ally to the outgoing leader who is considered to have strong ties with more conservative segments of the conference.

“It's Thune’s to lose, but Cornyn’s going to make it close,” one GOP aide familiar with leadership dynamics told The Hill. “It's going to be bloody and rough, and money is going to matter.”

Sen. Rick Scott (R-Fla.) is also once again running for the post but is not expected to survive past the first ballot in what will be a secret tally on Wednesday. The vote will only include the members who will be in office once the 119th Congress convenes next year.

The outcome of Tuesday’s election will likely play a key role in who succeeds McConnell.

Thune was consistently on the road in support of Senate GOP candidates throughout October, appearing for all of those in competitive races, save for Kari Lake in Arizona, during the final month, according to a source familiar with Thune’s operation.

He also raised more than $33 million across his accounts, the National Republican Senatorial Committee (NRSC) and the party’s fleet of candidates, the source added.

© The Hill