Donald Trump is the punishment the Republican Party deserves for rejecting every proposal by President Barack Obama, Sen. Harry Reid said Thursday morning.

"If [Majority Leader Mitch McConnell] wants to know where Donald Trump came [from], he should take a look in the mirror," Reid said in a speech at the left-of-center Center for American Progress Action Fund, a think tank based in Washington, DC.

Reid squarely blamed the Kentucky senator for helping create the "wasteland" in which Trump's fearmongering and xenophobia could flourish in the conservative movement.

He also directly challenged McConnell and House Speaker Paul Ryan to disavow Trump, accusing them of trying to "have it both ways" by criticizing Trump’s most outrageous remarks while pledging support to whoever is the party’s eventual nominee.

McConnell and Ryan should either clearly denounce Trump, Reid said, or put on "Make America Great Again" hats and stand behind the billionaire at a press conference.

"There’s no gray area here," he said. "It’s time for Sen. McConnell and Speaker Ryan to find the backbone to say: 'Enough, Trump, enough.'"

Why Reid wants to force Republican leaders' hand on Trump

The political incentives driving Reid's attack today couldn't be clearer.

If McConnell and Ryan disavow Trump now, they risk fracturing the Republican Party and inciting a revolt by the millions of voters who have supported Trump's campaign.

But if they embrace Trump, they'll be handing Democrats an incredibly powerful weapon: the ability to brand the entire GOP as the vehicle of Trump's highly unpopular extremism.

That's a no-win predicament for the Republican leadership, one that Reid seemed to revel in during his speech on Thursday. And the stakes couldn't be higher: Democrats seeking to retake the Senate are in striking distance, giving Reid extra motivation to force blue-state Republicans in Congress to take a stand on Trump.

"Why are they waiting to withdraw their support? What more do they need to see?" Reid said.

The answer is clear: The more voters flock to Trump, the less the Republican leadership can afford to declare all-out war on him. But if McConnell and Ryan find themselves in an impossible position now, Reid argued it's one of their own making.

"After years of refusing to denounce birtherism, McConnell and Ryan are now supporting the most prominent birther in the nation," Reid said. "This is precisely the kind of moral cowardice that enabled the rise of Trump."

An almost joyful liberal interpretation of Trump’s rise

Reid extensively condemned Trump as a dangerous force in American politics, as someone who peddles racism, and as a conspiracy theorist.

But it was hard to avoid the impression that at least a part of Reid was enjoying watching Republicans’ flailing inability to stop the Trump contagion.

"Because of the inaction they sowed, they’re reaping Donald Trump’s candidacy," Reid said of the Republican leadership. "Donald Trump’s style of no-holds-barred politics was forged in the Senate Republican caucus."

Reid repeatedly connected the choices of longtime political adversaries to the chaos devouring their party. At one point, a small smile began spreading across his face before quickly vanishing.

"The Republican establishment acts bewildered, but they should not be bewildered," Reid said. "For eight years … they’ve replaced thoughtful engagement with hatred and resentment."

Reid spoke wistfully about working with Trent Lott, once much hated by the left as corrupt, and other Republicans in the years before Obama's presidency. That bipartisan age, Reid said, was ruined when McConnell convinced Republicans to sign on to "the big lie: If Obama supports it, it won’t help you."

"On issue after issue, Republican leaders faced a choice: Help their constituents put food on the table, literally, or stick it to President Obama. Time after time, Republicans chose to stick it to President Obama," Reid said.

The tension in Reid’s comments about his Republican foes

Reid said Republicans had encouraged the "darkest forces" in America with their refusal to work with President Obama shortly after his inauguration.

Over the course of nearly an hour, Reid attributed Trump's rise to the individual decisions made by politicians who could have chosen otherwise.

"Republican leaders created the drought conditions; Donald Trump has simply struck the match," he said.

But when asked by a member of the audience why the Senate couldn't strike more compromises, Reid pointed instead to structural forces that made it impossible for any members of the Republican Congress to cooperate with Democrats.

"There’s no one to work with anymore," Reid said. "They’re afraid."