By Megan Cassella
WASHINGTON - Democratic front-runner Hillary Clinton will assail the prospect of a Donald Trump-appointed U.S. Supreme Court justice on Monday, her campaign said, as she seeks to regain momentum from party rival Bernie Sanders, the winner of three weekend nominating contests.
Clinton will criticize U.S. Republican senators for refusing to consider President Barack Obama's nominee, Merrick Garland, and voice concern about any nominee from Trump, front-runner in the Republican race for the Nov. 8 presidential election, her campaign said.
A Trump nominee to fill the position vacated with the Feb. 13 death of Justice Antonin Scalia would seek to curb Americans' rights and empower corporations, Clinton will say in the speech urging Republicans to do their jobs and consider Garland.
Senate Republicans, including Judiciary Committee Chairman Chuck Grassley, have refused to meet with Garland, a moderate federal appeals judge. Clinton's campaign said she would urge Grassley to give Garland a hearing.
Clinton will speak in Wisconsin, which holds a primary nominating contest on April 5.
Sanders' wins in Alaska, Hawaii and Washington chipped away at Clinton's overwhelming lead in the race for the 2,382 delegates needed to take the Democratic nomination at the party's Philadelphia convention in July.
Trump also plans to campaign in Wisconsin this week as he seeks to build his lead over Republican rivals, U.S. Senator Ted Cruz of Texas and Ohio Governor John Kasich.
Trump has won 738 of the 1,237 delegates needed to take the Republican nomination at its July convention in Cleveland. Cruz has won 463, while Kasich, who has vowed to stay in the race until the convention, has won 143, The New York Times said.
In the latest sign of unpredictability in the Republican race, Trump vowed to sue at least one state over its delegate allocation ahead of the convention.
"Just to show you how unfair Republican primary politics can be, I won the State of Louisiana and get less delegates than Cruz-Lawsuit coming," Trump wrote on Twitter.
Last week, the Wall Street Journal detailed the delegate fight in the state, which gave Trump and Cruz 18 each after its March 5 contest but has 10 others up for grabs.
Trump gave no other details and his campaign spokeswoman Hope Hicks had no comment.
Cruz spokesman Ron Nehring blasted Trump in a tweet and urged him to read up on party rules.
(Reporting by Megan Cassella; Additional reporting by Doina Chiacu, Susan Heavey and Ginger Gibson; Editing by Meredith Mazzilli and Howard Goller)