The Democratic Party is feeling the sting of rejection.

Last week, the Democratic National Committee backed a resolution supporting Black Lives Matter, which aims to end racial disparities in the criminal justice system.

Then, on Sunday, the official Black Lives Matter Network, which consists of 26 chapters nationwide, said it appreciates the gesture but won't return the favor.

"We do not now, nor have we ever, endorsed or affiliated with the Democratic Party, or with any party," the group said in a statement. "The Democratic Party, like the Republican and all political parties, have historically attempted to control or contain Black people’s efforts to liberate ourselves. True change requires real struggle, and that struggle will be in the streets and led by the people, not by a political party."

Ouch.

This may come off as harsh. But the statement is in line with recent clashes between Black Lives Matter activists and Democratic presidential candidates at public events. And there's a good reason for this type of response: Both Republicans and Democrats supported tough-on-crime policies that disproportionately impacted black communities. It's going to take a lot more than a resolution to mend these deep-seated issues.

Democrats are just as much to blame for "the new Jim Crow"

Democrats were big supporters — and even drivers — of tough-on-crime policies that drove mass incarceration and the war on drugs. But both of these policies have disproportionately hurt black Americans, becoming the subject of much scorn for the Black Lives Matter movement — even earning the label "the new Jim Crow" from civil rights advocate Michelle Alexander.

As a senator, for instance, Vice President Joe Biden was a sponsor and co-author of several of the tough-on-crime laws in the 1980s and '90s. And Hillary Clinton and Bernie Sanders, along with Biden, supported the 1994 Violent Crime Control and Law Enforcement Act, which imposed tougher prison sentences, increased funding for prisons, put more police on the streets, and awarded police with grant money for drug-related arrests that many black communities now see as a cause for police harassment.

These laws helped cause, for example, the explosive growth of the prison population from the 1980s to 2000s:

And a disproportionate percentage of the growing prison population was black:

At the time, Democrats supported these policies because the general public wanted them. From the late 1960s to the early 1990s, crime was unusually high. The country was still coming off what was perceived as a crack cocaine epidemic, in which the drug ran rampant across urban streets and fueled deadly gang violence. So Americans, by and large, demanded their lawmakers do something — and politicians from both parties reacted with mass incarceration and other tough-on-crime policies.

Since then, criminal justice experts have come to agree that these laws were overly punitive. Although mass incarceration and more police contributed to some of the crime drop since the 1990s, many experts say that very early on, incarceration reached the point of diminishing returns — there are only so many serious criminals out there, and after a certain point the people getting put in prison aren't people who'd be committing crime after crime on the street. As a result, there are a lot of people in prison who don't need to be for the sake of public safety — and a disproportionate number of those people are black.

Some Democrats have admitted that they made the problem worse. Earlier this year, Bill Clinton stated, "I signed a bill that made the problem worse, and I want to admit it." Hillary Clinton has made similar comments. And Biden spent his last few years in the Senate trying to repeal some of the laws he helped pass.

But advocates by and large feel the damage is done. So for them, it's not enough for Democrats to acknowledge their mistakes. Democrats also have to show that they learned from their mistakes — and back the kinds of policies that Black Lives Matter activists now demand. A party resolution falls far short of that.