Washington CNN  — 

Hillary Clinton’s Sunday entrance into the 2016 presidential race didn’t mute the lesser-known Democratic contenders – nor the committees trying to draft a heavyweight challenger for the party’s nomination.

The group Ready for Warren, which is recruiting Massachusetts Sen. Elizabeth Warren for a populist campaign, despite the freshman senator’s insistence she won’t run, said it will step up its efforts to entice their preferred candidate. The group insists Warren is better suited to take on Wall Street and address income inequality.

READ: Hillary Clinton launches second presidential bid

“With the 2016 race officially underway, we anticipate more Americans expressing their desire for a vigorous Democratic primary with Elizabeth Warren in it – a primary that would strengthen the eventual nominee, ensure Democrats are better positioned to win the general election, and give working families a champion in Washington,” the group’s campaign manager, Erica Sagrans, said in a statement.

Draft Biden, a similar group recruiting Vice President Joe Biden, offered a similar take.

“We’re seeing a fantastic response across the country to the idea of the Vice President running. People are amped for the Vice President to get in because 1) they love him and 2) they want there to be choice,” Marcus Ferrell, the group’s political director, said in a statement.

The three most likely challengers to Clinton stayed away from taking direct shots at her in statements their campaigns issued Sunday.

“Americans expect to interact directly with all candidates and prospective candidates,” a spokesman for Jim Webb, the former Virginia senator, said. “Sen. Webb will continue to travel the country, talking and listening to the people.”

SEE: GOP rivals take aim at Clinton

Vermont Sen. Bernie Sanders, an independent who has said he’d run to represent liberal positions, called Clinton and “experienced and well-qualified leader” but listed a number of issues he said she needs to speak to during the race.

Among them: Income inequality, stagnant wages, climate change and the influence of money in politics.

“I hope that Secretary Clinton will speak out on these and other important issues in the days and weeks ahead,” Sanders said in a statement.

And former Maryland Gov. Martin O’Malley’s spokeswoman said his decision on whether to run won’t be influenced by Clinton’s entrance.

“All across the nation, he’s heard from Democrats that they are looking for someone who offers strong progressive values, new leadership, and the experience of getting real results. The Democratic Party will benefit from a robust issues debate, and – should Gov. O’Malley decide to enter the race – he will bring one,” O’Malley spokeswoman Lis Smith said.

Still, Clinton quickly got the backing of two Democratic senators.

Sen. Tim Kaine, D-Virginia, a potential vice presidential short-lister, said Clinton is “absolutely the right person for the job, as well as the partner I want to have in the White House as I enter my fifth year in the Senate.”

“With decades of experience and deep knowledge of both domestic and foreign policy, she is uniquely qualified to build on the progress of the past six years and lead our country in an increasingly challenging world,” Kaine said in a statement.

Retiring Sen. Barbara Mikulski, D-Maryland, the influential former Senate Appropriations Committee chairwoman, started her endorsement of Clinton by saying, “Whoopee!”

“I’m ready for Hillary. And America is ready for Hillary. She is going to break that glass ceiling once and for all,” Mikulski said. “When we put Hillary in the Oval Office, she will make history and change history. She will take our hopes and dreams with her.”