WASHINGTON — The partisan political divide over the potential nomination of U.N. Ambassador Susan Rice to be secretary of state intensified Sunday with Republicans questioning her fitness for the job and Democrats defending her.

Republican senators said they remain deeply concerned over Rice's statements about the Sept. 11 attack on the U.S. diplomatic post in Benghazi, Libya, and suggested her motive was to help President Barack Obama's re-election chances. Democrats, meanwhile, said they saw no reason the statements should disqualify her if she's nominated.

At issue is the explanation Rice offered in a series of talk show appearances five days after the attack that killed U.S. Ambassador Chris Stevens and three other Americans.