New York City Mayor Bill de Blasio wants to put income inequality at the forefront of national politics. (Andrew Burton/Getty Images)

New York Mayor Bill de Blasio plans to host a meeting of leading progressive elected officials and activists at Gracie Mansion on Thursday with the explicit goal of forcing the issue of income inequality to the forefront of the national political debate and the 2016 elections.

In a telephone interview Wednesday, de Blasio said his frustrations with the messaging by Democratic candidates during the 2014 midterms and the overall failure among elected officials to tackle income inequality head-on led him to conclude that progressives must be more aggressive in elevating the issue.

“As a Democrat, I am very disappointed that my party has not spoken with a clearer voice on this issue,” de Blasio said.

The mayor said that influencing the dialogue in the 2016 presidential race is not the sole purpose of the effort he hopes to organize.

He would not directly address whether he thinks former secretary of state Hillary Rodham Clinton should outline bold proposals to reduce income inequality.

The mayor was Clinton’s Senate campaign manager in 2000, and she attended his inauguration in 2013, along with her husband, former president Bill Clinton. De Blasio was elected mayor running on an unabashedly liberal platform, while both Clintons have been identified more with centrist Democratic ideas. Hillary Clinton is expected to launch her presidential campaign this month.

“On presidential candidates in general, my take is, I don’t talk about anyone until they are a declared candidate,” de Blasio said. “But I think many of us feel profound dissatisfaction at the state of the debate in general. I cannot identify any declared candidate who is presenting a holistic vision here. In 2014, many [Democrats] went out of their way to avoid the issue.”

He praised President Obama for highlighting income inequality in this year’s State of the Union address and noted that some Republicans and some business leaders have at least begun to make reference to the issue. But he said that beyond Obama’s January speech, nothing since then “suggests a course correction” on the part of elected officials or prospective candidates.

Asked to assess why Democrats in particular have not been more aggressive on the issue, he said, “A lack of leadership and a lack of imagination underlying all of it.”

He cited two other obstacles: timidity on the part of political strategists and party consultants to confront the issue more robustly; and the influence of money in politics. “Platform, vision and message have been replaced by decisions about resources,” he said. “That’s not a winning hand.”

De Blasio said Thursday’s gathering will include about 12 to 15 people from around the country. He said a list of names will be made available after the meeting. Among those expected to attend are Sen. Sherrod Brown (D-Ohio) and Nobel Prize-winning author Toni Morrison.

One person who will not be there is Sen. Elizabeth Warren (D-Mass.), a leading advocate for a more robust set of politics to reduce the power of big banks and financial institutions, and address the needs of middle-class families. De Blasio said a scheduling conflict will prevent Warren from attending.

The meeting marks the beginning of what the mayor hopes will become a larger and sustained effort. He will take his message about addressing income inequality to Iowa later this month, a trip first reported by Capital New York. The mayor also will speak at a Democratic Party dinner in Wisconsin at the end of April.

De Blasio was invited to speak at Drake University in Des Moines by former Iowa senator Tom Harkin. Harkin was one of nearly 200 Democrats in Iowa and New Hampshire who recently signed a petition calling on Clinton and other Democratic presidential candidates to campaign in 2016 on big, bold populist ideas of the kind often associated with Warren.

De Blasio said one major goal of Thursday’s meeting and subsequent organizing efforts will be to advance specific policies that he and other progressives believe have not received enough attention or support from elected officials.

He highlighted the goal of a more progressive tax code as central in that agenda. “You cannot address this [income inequality] without addressing progressive taxation that clearly will ask more of the wealthy,” he said.

The mayor said he is as concerned about jump-starting the discussion with current elected officials as he is about affecting the coming presidential debate. And he underscored the challenge of trying to create genuine political momentum behind policies that many elected officials have long resisted or opposed.

“I think this is going to take a lot of repetition and a lot of organizing,” he said, adding, “We don’t address this issue at our national peril. . . . Progressives have an obligation not to accept the status quo. . . . We’re going to try to raise the bar here.”