UPDATE:

Six challengers are trying to replace U.S. Senator Johnny Isakson this year.

There are also races for three Central Georgia congressional seats.

The candidates for U.S. Senate are Cheryl Copeland, a project manager from Hiram; James Knox, IT specialist, DeKalb County; Jim Barksdale, businessman, Atlanta; John Coyne, CEO, Alpharetta, all Democrats, and Republicans Derrick Grayson, a network engineeer from Redan, and Mary Kay Bacallao, a college professor from Fayetteville.

Isakson, a Republican from Atlanta, is seeking a third term in the Senate.

Congressmen Sanford Bishop, Austin Scott and Rick Allen all face challengers.

Running against Bishop in the 2nd Congressional District are Bobby Scott, attorney, Columbus; Diane Vann, a nurse from Macon; and Greg Duke, an optician from Leesburg. They're all Republicans.

Bishop,a Democrat, has represented the district since 1993, The district includes Crawford, Macon, Peach, Dooly and Taylor counties and most of Bibb County.

A Democrat, James Neal Harris from Gray, and Republican, Angela Hicks of Macon, are both running against Congressman Austin Scott in the 8th District. Scott, a Republican from Tifton, is looking for a third term.

The district includes Monroe, Jones, Wilkinson, Twiggs, Houston, Bleckley, Pulaski, Dodge, Telfair and Wilcox counties and part of Bibb County.

And three people are running against Rick Allen, a Republican from Augusta, in the 12th Congressional District. They are Eugene Yu, a Republican from Evans, who is retired; Joyce Nolin, a Democrat and retired educator from Evans; and Tricia Carpenter McCracken, a Democrat from Augusta who describes herself as a freelance journalist who also works in historic preservation.

Allen, a Republican from Augusta, is seeking a second term.

The district includes Treutlen, Laurens and Wheeler counties.

Jody Hice has no opposition for re-election in the 10th Congressional District. He is a Republican from Bethlehem and a minister. The district includes Baldwin, Hancock, Washington and Johnson counties.

Primaries will be decided May 24; the final election is in November.

Qualifiers for Congressional seats:

U.S. Senate

Cheryl Copeland (D), Hiram

Derrick Grayson (R), Redan.

James Knox (D), DeKalb County

Jim Barksdale (D). Atlanta

John Coyne (D), Alpharetta

Johnny Isakson, (R), Atlanta (i)

Mary Kay Baccallao (R) Fayetteville

2nd Congressional District (Crawford, Macon, Peach, Dooly and Taylor counties and most of Bibb County)

Bobby Scott (R), Columbus

Diane Vann (R), Macon

Greg Duke (R), Leesburg

Sanford Bishop (D), Columbus (i)

8th Congressional District (Monroe, Jones, Wilkinson, Twiggs, Houston, Bleckley, Pulaski, Dodge, Telfair and Wilcox counties and part of Bibb County)

Austin Scott (R), Tifton (i)

James Harris (D), Gray

Angela Hicks (R) Macon

10th Congressional District (Baldwin, Hancock, Washington and Johnson counties)

Jody Hice (R), Bethlehem (i)

12th Congressional District

Eugene Yu (R), Evans

Joyce Nolin (D), Evans

Rick Allen (R), Augusta (i)

Trisha Carpenter McCracken (D), Augusta

UPDATE: noon, Thursday.

A Macon native has joined the race for Georgia's U.S. Senate seat.

He is businessman Jim Barksdale, a Democrat who's challenging incumbent Johnny Isakson.

According to his news release, Barksdale is a lifelong Georgian, who was born in Macon and attended Atlanta Public Schools. He started a a company in Atlanta, Equity Investment Corporation. He says he's also served on the Board of Councilors at The Carter Center since 2008.

Isakson,a Republican, is seeking a third term. Three other Democrats and one Republican are also running.

Also, Diane Vann of Macon, a registered nurse, has qualified to challenge U.S. Rep. Sanford Bishop. Vann, a a Republican, has run twice before.

Qualifiers so far:

U.S. Senate

Cheryl Copeland (D), Hiram

Derrick Grayson (R), Redan.

James Knox (D), DeKalb County

Jim Barksdale (D). Atlanta

John Coyne (D), Alpharetta

Johnny Isakson, (R), Atlanta (i)

2nd Congressional District (Crawford, Macon, Peach, Dooly and Taylor counties and most of Bibb County)

Bobby Scott (R), Columbus

Diane Vann (R), Macon

Greg Duke (R), Leesburg

Sanford Bishop (D), Columbus (i)

8th Congressional District (Monroe, Jones, Wilkinson, Twiggs, Houston, Bleckley, Pulaski, Dodge, Telfair and Wilcox counties and part of Bibb County)

Austin Scott (R), Tifton (i)

James Harris (D), Gray

10th Congressional District (Baldwin, Hancock, Washington and Johnson counties)

Jody Hice (R), Bethlehem (i)

12th Congressional District

Eugene Yu (R), Evans

Joyce Nolin (D), Evans

Rick Allen (R), Augusta (i)

Trisha Carpenter McCracken (D), Augusta

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UPDATE; noon, Wednesday.

Four challengers -- three Democrats and a Republican -- are running for Johnny Isakson's U.S. Senate seat.

The Democrats are Cheryl Copeland, a project manager from Hiram; James Knox, an IT specialist from DeKalb County; and John Coyne, a CEO from Alpharetta.

The Republican is Derrick Grayson, a network engineer from Redan.

Also, a new challenger has filed to run against U.S. Rep. Sanford Bishop in the 2nd Congressional District. He is Greg Duke,an optician from Leesburg, who ran unsuccessfully in 2014.

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Central Georgia congressmen Austin Scott and Sanford Bishop both have challengers for this year's election.

According to the Georgia Secretary of State's Office, Bobby Scott, an attorney from Columbus, qualified Monday to challenge Bishop.

Scott's a Republican.

Bishop is a Democrat from Columbus. He's represented the 2nd Congressional District since 1993.

The district includes Crawford, Macon, Peach, Dooly and Taylor counties and most of Bibb County.

James Neal Harris, a Democrat from Gray, qualified to challenge Scott in the 8th Congressional District.

Harris describes himself as a security consultant and private investigator.

Scott, a Republican from Tifton, has held the seat since 2011.

The district includes Monroe, Jones, Wilkinson, Twiggs, Houston, Bleckley, Pulaski, Dodge, Telfair and Wilcox counties and part of Bibb County.

Two people, Republican Eugene Yu and Democrat Trisha Carpenter McCracken, qualified Monday to run in the 12th Congressional District.

Rick Allen, a Republican from Augusta, won the seat in 2014.

Yu is from Evans and is retired. McCracken is also from Augusta and describes herself as a freelance journalist who also works in historic preservation.

The district includes Treutlen, Laurens and Wheeler counties.

So far, nobody has qualified to run against 10th District Congressman Jody Hice.

Hice, a minister from Bethlehem, in Barrow County, also won his seat two years ago. He's a Republican.

The district includes Baldwin, Hancock, Washington and Johnson counties

Also, two people, a Democrat and a Republican, have filed papers to challenge U.S. Senator Johnny Isakson.

They are Republican Derrick Grayson, a network engineer from DeKalb County, and Democrat James Knox, an Air Force veteran and information technology specialist from Evans in Columbia County.

Qualifying for the seats runs through Friday.

The Republican and Democratic primaries will be decided May 24.