Originally Published: 11 APR 23 08:18 ET

Updated: 11 APR 23 10:24 ET

By David Wright, CNN

(CNN) -- Bernie Moreno, a wealthy Ohio businessman, has filed paperwork to run for Senate in 2024 and challenge Democratic Sen. Sherrod Brown in what's likely to be one of the most competitive races of the upcoming cycle.

Moreno is now the second Republican to officially jump into the race after state Sen. Matt Dolan announced his candidacy in January.

Moreno mounted an unsuccessful campaign for Senate in 2022, loaning his campaign millions from his personal fortune before dropping out of the race ahead of the primary. His decision to drop out came after a meeting with former President Donald Trump, who would go on to endorse one of his rivals, J.D. Vance.

The Cleveland businessman's entry into the 2024 race sets up another potentially expensive and contentious primary in the state after the 2022 contest, which was driven by several self-funding candidates, was one of the costliest that year.

Other potential candidates who have expressed interest include 8th district Rep. Warren Davidson and Secretary of State Frank La Rose.

Brown is one of several vulnerable Democrats who the party is defending as it seeks to hold its slim majority in the upper chamber. Trump carried the state in 2016 and 2020, and Vance won the 2022 race by nearly 7 points despite a spirited challenge by Democratic Rep. Tim Ryan.

Still, Brown, seeking his fourth term, won his last race in 2018 by nearly 7 points, bolstering Democratic hopes that they can hang on in a state that has trended increasingly Republican over the last several election cycles. And Brown had more than $3.4 million stockpiled in Senate campaign account as of the end of last year.

Democrats, though, will be pressed to defend Brown amid a challenging map that includes other incumbents in similarly vulnerable positions, such as Sen. Joe Manchin in West Virginia and Sen. Jon Tester in Montana, along with an unpredictable three-way race in Arizona.

CORRECTION: This story has been updated to reflect that former President Donald Trump endorsed JD Vance in the 2022 Ohio Senate race after a meeting with Bernie Moreno.