Jeff Roberson, Associated Press
Democratic presidential candidate Hillary Rodham Clinton speaks during a campaign stop at Christ the King United Church of Christ, Tuesday, June 23, 2015, in Florissant, Mo.

ST. LOUIS — Hillary Rodham Clinton isn't expected to show at an annual convention of liberal activists and bloggers often courted by Democratic presidential candidates.

Netroots Nation organizers said Wednesday that Democratic presidential candidates Bernie Sanders and Martin O'Malley have confirmed their attendance at the July 16-19 conference in Phoenix.

Clinton's campaign cited a scheduling conflict, with commitments in Iowa on July 17 and Arkansas on July 18. Sanders and O'Malley plan to speak at the Iowa dinner.

About 3,000 activists are planning to attend the Netroots Nation convention, which will also feature Sen. Elizabeth Warren, D-Mass. Many liberals had hoped she would challenge Clinton for the nomination.

Clinton remains the dominant Democratic candidate but one of her challenges in the primaries will be generating support among some liberals who have been hesitant to back her campaign, wary of her willingness to rein in Wall Street excess and her past support of trade deals.

Clinton last appeared at Netroots Nation in 2007 — then called Yearly Kos — at a presidential forum that also included then-Illinois Sen. Barack Obama, former North Carolina Sen. John Edwards and others.

She received a tepid response from activists, some of whom disapproved of her vote in favor of the 2003 invasion of Iraq and her acceptance of campaign contributions from lobbyists.

Raven Brooks, Netroots Nation's executive director, said the conference is hopeful the Clinton campaign "will reconsider addressing this core progressive community who are most eager to hear from her."

Brooks said former Rhode Island Gov. Lincoln Chafee, a former Republican seeking the Democratic nomination, would not be invited to the event and organizers would monitor the presidential field to decide whether to invite others like former Virginia Sen. Jim Webb, who is exploring a campaign.

Follow Ken Thomas on Twitter at: http://twitter.com/kthomasdc. This story has been corrected to show that the conference was previously called Yearly Kos, not Year Kos.