Trailing the Democratic incumbent by a wide margin in the polls and fundraising, Harris likely will take those attacks right to Nelson on Monday night when they meet for the first of two televised debates before the Nov. 7 election.
The candidates will answer questions from a panel of Florida journalists at Nova Southeastern University in Davie. The one-hour debate will be carried live on all Florida public television stations.
They plan to meet again on Nov. 1 in another one-hour debate, moderated by Tim Russert from "Meet the Press" and carried on NBC affiliates statewide.
The debates are seen as critical for Harris, who has been unable to significantly chip away at Nelson's double-digit lead in the polls and doesn't have a lot of money left to get her message out in TV ads.
Harris, in a series of news conferences in the last month, has attacked Nelson as a "do-nothing liberal" whose values do not reflect those of more conservative Floridians.
Nelson's campaign has scoffed at her claims, questioning the Longboat Key congresswoman's credibility and noting that Nelson is widely considered a moderate senator. Nelson's statewide TV ads tout his record as a freshman senator and don't even mention Harris' name.
Harris has yet to run a TV ad since the primary, and most political experts doubt she will be able to close the gap between her and Nelson, even if she is able to saturate the state with ads in the coming weeks.
Nelson, 64, has been in Florida politics for more than three decades. He is seeking his second six-year term in the Senate.
Harris, 49, gained the adoration of the Republican rank-and-file — and the scorn of Democrats — in 2000 when as Florida secretary of state, she oversaw the recount that put George W. Bush in the White House. She won her congressional seat in 2002 and was re-elected in 1994.
She continues trying to repair the damage that has plagued her campaign all year.
Support was lacking initially from state GOP leaders who tried to recruit someone else to run. Campaign workers have defected in droves, she has made questionable public statements and has had to answer questions about her dealings with a corrupt defense contractor.
As of Sept. 30, she had less than $1 million in her campaign coffers, compared with $6.8 million for Nelson.