Political action committees are spending unlimited amounts in hopes of swaying a closely-watched U.S. Senate matchup.

Arizona Sen. Kyrsten Sinema raised a fraction of what her leading challengers brought in in the last quarter of 2023, raising new questions about her chances in what could be a bruising, three-way race.

Democratic Arizona Sen. Mark Kelly continued to widen his fundraising lead over Republican challenger Blake Masters, who still trailed the incumbent despite heavy spending by outside conservative groups.