The race is on among progressives who see an opening to Hillary Clinton’s left in several issues which are core concerns of the Democratic voting base. The topics of economic policy, energy policy, and foreign policy to name a few, have many liberal Democrats concerned about Hillary’s “establishment” record within the Democratic Party.

Enter Bernie Sanders, stage left. Report from the Des Moines Register:

Independent U.S. Sen. Bernie Sanders of Vermont, who has said he’s testing the waters for a 2016 presidential run, will be in Iowa again on Tuesday, Dec. 16.

Sanders will be the keynote speaker at the 2014 Progress Iowa Holiday Party at the Meadows Events and Conference Center in Altoona. He will “focus his remarks on creating a government that works for all Americans, not just the wealthy and well-off,” according to a news release from Progress Iowa, a liberal group.

The keynote speaker at the 2013 event was former Montana Gov. Brian Schweitzer.

In a statement, Sanders said: “Big majorities of Americans understand that that the middle class is disappearing; unemployment is too high; wealth and income inequality is a threat; that corporate tax loopholes must be closed; that Social Security, Medicare and Medicaid must not be cut; that global warming threatens our planet and that billionaires should not be allowed to buy elections. We should build on that unity. Progress Iowa has provided a strong voice in the fight for America’s middle class, and I’m excited to speak with their supporters in December.”

Sanders made trips to the presidential testing grounds of Iowa in May, September and October.

Sanders won’t win the nomination, but he could serve as another voice, along with Elizabeth Warren, that will make Hillary engage on topics she’ll likely be trying to avoid before entering the general election.