Tennant also pledged to promote college affordability, focus on small business, fight for a balanced budget and fix elements of the Affordable Care Act, commonly known as Obamacare.
In describing other campaign focuses, Tennant alluded to connections with Rockefeller and Byrd. She did not mention Manchin.
Pointing to Rockefeller, Tennant did say it is important to diversify West Virginia's economy. She mentioned the Toyota facility in Buffalo that Rockefeller helped bring to the state as an example of job creation she can emulate.
When referencing Byrd, Tennant promoted his ability to bring mountains of federal money to the state to create facilities that can foster growth in research and technology jobs.
Rockefeller issued a statement strongly supporting Tennant. He clearly criticized Capito and congressional Republicans, saying West Virginia cannot afford to allow the seat he currently occupies fall to "the party of Paul Ryan and Mitch McConnell."
"(Tennant) has an unwavering commitment to public service and, most importantly, a ceaseless passion for the people of West Virginia and our challenges," Rockefeller said in the statement.
"Republicans have offered West Virginia no solutions to the problems we face, and instead take action against us again and again — voting to block mine safety reforms in the wake of the UBB tragedy, pushing to privatize Medicare and Social Security, and protecting their political friends on Wall Street at the expense of West Virginians.
Manchin also came out in support of Tennant, calling her a proven statewide leader.
"I have known Natalie and her family for many years and a dedication to public service runs deep in her blood," Manchin said.
"Natalie Tennant, Congressman Nick Rahall and Nick Casey along with West Virginia Democrats from the county and city level up to the federal level have my support," Manchin said.
Rep. Nick Rahall, D-W.Va., represents the third congressional district, in the southern portion of the state. Casey, former Democratic state party chairman, is running for the seat Capito currently holds.
Tennant's husband, state Sen. Erik Wells, D-Kanawha, and their daughter, Delaney, joined her on stage for the announcement. Several Democrats — including Gov. Earl Ray Tomblin, Senate President Jeff Kessler, Speaker of the House Tim Miley and House Majority Leader Harry Keith White — all stood behind Tennant during her speech.
State Democratic Party Chairman Larry Puccio said he was unable to attend any of Tennant's events Tuesday due to a family emergency, but he issued a statement of support early in the day.
Christine Campbell, president of the state chapter of the American Federation of Teachers, and Kenny Perdue, president of the state chapter of the AFL-CIO, attended. Unions have traditionally supported Democrats in the state; Campbell said the unions still needed to go through a formal selection process before endorsing a candidate.
Major Gen. Allen Tackett, former leader of the state National Guard, is serving as campaign chairman for Tennant's campaign.
Tennant planned further campaign announcement events Tuesday evening at West Virginia University's Mountainlair and Wednesday in Wheeling and Martinsburg.
Capito announced her candidacy in late 2012, weeks before Rockefeller publicly announced he would not seek re-election. She reported having nearly $3 million on hand for the campaign halfway through the year, a figure that will certainly grow.
After her speech, Tennant said she didn't think the current difference in fundraising would be an issue.
The race has already garnered a great deal of national attention. National Republicans believe the seat is vulnerable to switch to the GOP after decades of Democratic control.
If Tennant and Capito win their primaries, it would guarantee a female senator for the first time in West Virginia history. It would also be only the third time in U.S. history where two female candidates from major parties have faced off in a race without an incumbent, according to Smart Politics, a political website operated by the University of Minnesota.
National political prognosticators The Rothenberg Political Report and Larry Sabato's Crystal Ball rate the race as "leans Republican," giving the GOP a slight advantage.