Black aldermen attempting to congratulate African-American contractors that won the right to help build the Obama Presidential Center in Jackson Park were drowned out Wednesday by protesters demanding that former President Barack Obama put it in writing.

The clash between black elected officials who are willing to take former President Obama at his word and neighborhood activists demanding a “community benefits agreement” echoed through the hallways outside the City Council chambers on the second floor of City Hall.

The Black Caucus called the news conference to applaud the decision to award 51 percent of all construction contracts to companies owned by minorities and to congratulate the so-called “Presidential Partners Consortium” comprised of the city’s largest Africa-American-owned construction firms.

Protesters chanting, “C.B.A.” and “Shame,” had other ideas. They were determined to drown out the aldermen and make their voices heard.

The raucous demonstration was led by Jitu Brown, who used similar, in-your-face tactics during the drive that forced Mayor Rahm Emanuel’s hand-picked school board to save Dyett High School.

“We cannot take the president’s word on the fact that they’re not gonna push African-Americans out with the Obama Presidential Center. There is no history that says their word is worth anything,” Brown said.

“What we need is an in-writing community benefits agreement that says that people who live in those communities will benefit — not in a profiteering way, but jobs, investment in neighborhood elementary schools, transportation infrastructure. That is not a lot to ask. In the case of the Staples Center in Los Angeles, it kept people in their communities.”

Brown was asked why he is so convinced that promises made by the nation’s first African-American president won’t be kept.

“The situation will not be different because our African-American president endorsed school privatization — the closing of schools all across the United States. Our African-American aldermen have sat by while 50 schools closed in the city of Chicago. And it had a harmful effect on Chicago’s children,” Brown said.

“Just because you are African-American does not mean that you walk with the values of people that live in those communities. We’re tired of people saying ‘I’m from the neighborhood.’ Who is your allegiance to?”

Ald. Leslie Hairston (5th) could barely be heard over the protesters’ chants.

She argued that the construction contracts awarded by the Obama Presidential Center provided “more than any C.B.A. that they came up with,” referring to the demonstrators.

“They not only vetted these groups — these construction companies. They actually pulled the records to make sure that they were not just fronts,” Hairston said.

“So, I congratulate them for the hard work they’ve been doing to make sure that there is African-American representation in this project.”

Although the protesters are threatening political retribution against black aldermen who refuse to stand with them, Hairston stood her ground.

“It does not make sense to put this in writing because there is so much more that we don’t know that we are just now learning. I don’t want to commit us to just thinking in a narrow box,” Hairston said.

“This has never been done in an urban setting. There are a lot of things we’re discovering as we move forward with this that we need to include and work on.”

On a related matter, Emanuel disclosed Wednesday that he’s counting on state funding to bankroll the $100 million-plus widening of Lake Shore Drive proposed to acomodate traffic diverted by the closing of Cornell Drive.

The mayor also confirmed rampant speculation that there would be a branch of the Chicago Public library located within the Obama Presidential Center.

A neighborhood library “could be transformative at that location,” the mayor said.