Election 2024: Donald Trump selects his campaign manager as incoming White House chief of staff

Four polling locations in Navajo County, Arizona, received bomb threats, according to the state's top election official.

"As to bomb threats in Arizona, the threats pertained to four specific locations in Navajo County only," Arizona Secretary of State Adrian Fontes said at a press conference. "These are unsubstantiated threats."

Fontes said his office has reason to believe the threats are from Russia, but clarified that hasn't been confirmed.

"I don't know that I'm at liberty to reveal anything more than my solid suspicion grounded in information that I don't know that I can share yet," Fontes said.

No polling locations were closed due to the bomb threats, Fontes said.

Isolated voting delays at several polling places around the country have prompted local officials to seek voting-hour extensions, which typically happens during every election cycle.

Among those sites whose hours have been extended are the following:

Cobb County, Georgia (20 minutes)

A judge granted Cobb County's request to keep two polling locations open an additional 20 minutes until 7:20 p.m. ET because of delayed openings due to "equipment issues," the county said in a statement.

Gwinnett County, Georgia (58 minutes)

A judge granted Gwinnett County's request to keep two polling locations open for an additional 58 minutes until 7:58 p.m. ET due to a security threat prompted a temporary evacuation earlier today.

Luzerne County, Pennsylvania (90 minutes)

A judge granted Luzerne County's request to extend voting for 90 minutes until 9:30 p.m. ET after one polling location in Laflin opened late.

Cambria County, Pennsylvania (2 hours)

A Pennsylvania judge ordered voting hours to be extended for two hours in Cambria County after scanners there were not able to read ballot markings and tabulate votes.

Wilson County and Burke County, North Carolina (30 minutes)

The North Carolina State Board of Elections approved extending the voting hours by 30 minutes at two precincts after both opened late this morning due to technical issues.

Fulton County, Georgia (various)

Due to threats today that required brief evacuation of five different polling locations, the Superior Court of Fulton County issued a ruling this afternoon allowing extension of voting hours at the Etris Darnell Community Center until 7:45 p.m. ET, C.H. Gullatt Elementary School until 7:15 p.m. ET, Southwest Arts Center until 7:43 p.m. ET, Northwood Elementary School until 7:45 p.m. ET and Lake Forest Elementary School until 7:10 p.m. ET

A federal judge has rejected an RNC lawsuit seeking to block some Georgia counties from accepting ballots that were hand-delivered over the weekend and Monday, according to Marc Elias, a lawyer working for Vice President Kamala Harris' campaign.

Judge R. Stan Baker -- who was appointed by former President Donald Trump -- said the lawsuit from Republicans "does not withstand even the most basic level of statutory review and reading comprehension," per Elias.

Republicans had claimed that the seven Georgia counties that were accepting hand-delivered mail-in ballots after the early voting period were violating the law.

Americans are going to the polls Tuesday to cast their ballots in the historic election between Vice President Kamala Harris and former President Donald Trump.

Surveys ahead of Election Day found the two candidates in a virtual dead heat nationally and in several key swing states.

Broad economic discontent, sharp divisions about the nation's future and polarized views of the major-party candidates mark voter attitudes nationally in ABC News' preliminary exit poll results.

The state of democracy prevailed narrowly as the most important issue to voters out of five tested in the exit poll.

READ MORE | 2024 exit polls: Fears for American democracy, economic discontent drive voters