Republicans are optimistic about their chances of winning control of the Senate in the upcoming general election due to strong GOP support in the South and Midwest, The Hill reported.

The upcoming retirement of independent Sen. Joe Manchin, I-W.Va., has Republicans looking to pick up his seat in the typically conservative-leaning state, while poor polling results for Sen. Jon Tester, D-Mont., has the Cook Political Report rating the race for his seat as "lean Republican."

The GOP will take the majority in the Senate if the party wins both of these races and staves off defeat in any other Senate elections. Although Democrats hope to unseat Sen. Ted Cruz, R-Texas, and Sen. Rick Scott, R-Fla., both are favored to win, according to Cook.

Cook also recently changed its rating for the race for the seat of Sen. Tammy Baldwin, D-Wis., from "leans Democrat" to "toss-up."

GOP pollster Jim McLaughlin told the Hill: "I've been polling in Wisconsin for a long time. Everybody says it's a Democratic state, but Ron Johnson's gotten elected three times. And how many times did Scott Walker win there? It really is the ultimate swing state."

• Cook Political Report: Key Wisconsin Senate Race Now 'Toss-Up'
• Report: Montana Senate Race Now Leans Republican