Indiana Republican Mike Braun is claiming a Brett Kavanaugh surge, citing internal campaign polling with the businessman leading Democratic Sen. Joe Donnelly in the days after the Supreme Court justice was confirmed.

The survey of 800 likely voters, conducted Oct. 14-17, showed Braun with a 44-40 percent advantage over Donnelly, who voted against Kavanaugh's confirmation after a nasty partisan battle that saw his nomination rocked by uncorroborated allegations of sexual misconduct. Libertarian Lucy Brenton was at 7 percent in this poll, which had a margin of error is 3.46 percentage points.

"Since Senator Donnelly committted the equivalent of political suicide by voting against Justice Kavanaugh a little more than two weeks ago, the bottom has fallen out of his campaign," reads a Braun campaign polling memorandum from the Republican nominee's top strategists, Jon Kohan and Josh Kelley.

Braun and Donnelly are locked in a tight race in Indiana, a Republican-leaning state that voted overwhelmingly for President Trump in 2016 and that is the home state of Vice President Mike Pence.

[Also read: GOP senators hope Kavanaugh fever lasts until midterms]

Donnelly hasn't faded. The blue collar Democrat from Northern Indiana still holds a 3 point lead in the polling average despite a rather a liberal voting record. But Republicans are more confident about Braun's prospects in the aftermath of Kavanaugh's confirmation, after previously complaining about their nominee's struggle to break through.

To be sure, Donnelly's "no" vote could hurt him with Trump loyalists whose cross-over votes he needs to win, and the partisan spat has generally energized Republican voters in red states who were less enthusiastic about voting in the midterm elections.

In Braun's internal campaign poll, Donnelly's favorable/unfavorable rating was driven upside down by the Kavanagh episode, landing at 41 percent favorable, 42 percent unfavorable. In the survey, Braun was rated 41 percent favorable, 34 percent unfavorable.