MADISON, Wis. (AP) — The Latest on Wisconsin U.S. Senate race (all times local):

1:25 p.m.

Republican U.S. Senate candidate Leah Vukmir says she's "very confident" she will win the state party endorsement at the GOP convention next month.

Vukmir said Tuesday that she's worked hard to win the backing of Republican Party activists who serve as delegates at the convention. They will vote on whether to endorse her or GOP rival, Delafield businessman Kevin Nicholson.

Nicholson's campaign says in an April 5 memo that Vukmir is focusing too much on winning the endorsement at the detriment of raising money and being in position to take on Democratic incumbent Sen. Tammy Baldwin.

Vukmir says Nicholson was "insulting" party activists and he doesn't understand Wisconsin politics. Vukmir says, "I've always respected the work of the grass roots."

The winner of the state party endorsement is given money, access to party staff and other resources.

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11:59 a.m.

Republican U.S. Senate candidates Leah Vukmir and Kevin Nicholson are sparring over the importance of winning the state GOP endorsement.

Nicholson last week released a memo downplaying the endorsement to be voted on at the state Republican Party convention next month, while criticizing "party insiders and establishment figures" for supporting Vukmir.

Vukmir's campaign says in an unsigned statement Tuesday that Nicholson is being "childish and arrogant" for dismissing party activists. The Vukmir campaign says Nicholson was treating activists who have driven Republican victories in recent years like "garbage."

Nicholson's memo says Vukmir has sacrificed fundraising and building her campaign to focus on winning the party endorsement. The memo says getting anything less than 85 percent of the endorsement vote would be an "astonishing underperformance" for her.