As times improve and the war [in Iraq] ends we will begin to introduce more and more elements familiar to my style.The show was known for Olbermann's fast-paced rhetoric, historical and pop culture references, and liberal commentary.

The show has been the source of controversy owing to these criticisms, as well as the host's ongoing commentary against Fox News and his feud with its leading primetime personality Bill O'Reilly.

He criticized Fox and O'Reilly for purportedly deceiving their viewers in service to their alleged right-wing biases, frequently including the latter in Countdown's "Worst Person in the World" segment.

[11] O'Reilly and other Fox personalities accused MSNBC of facilitating a liberal media bias, in what Olbermann described as a war of attrition intended to force him into silence.

Issues addressed in the Special Comments dealt with the Bush Administration's foreign and domestic policies, mainly the wars in Iraq and Afghanistan.

[19] In 2009, left-wing political analyst Lawrence O'Donnell hosted Countdown for an extended period, leading to the eventual launch of his show The Last Word.

[20] In response, MSNBC President Phil Griffin suspended Olbermann indefinitely without pay on November 5 for violating a network policy regarding political contributions which required prior approval from management.

[21] An online petition calling for his reinstatement received over 250,000 signatures,[22] and two days after the suspension began, Griffin announced that Olbermann would return to the air starting with the November 9 program.

Media critic Howard Kurtz, former MSNBC anchor David Shuster, and an anonymous NBC News executive[26] said that Olbermann's 2010 suspension was a more likely precipitating factor in Countdown's cancellation.

[29] On May 11, Olbermann announced that Daily Kos founder Markos Moulitsas, filmmakers Michael Moore and Ken Burns, and comedian Richard Lewis would become contributors to the new Countdown.

[30] During a June 16 interview on NBC's Late Night with Jimmy Fallon, Olbermann further announced that journalists Matt Taibbi and Jeremy Scahill, former Nixon administration official and author John Dean, actor Donald Sutherland, and astronomer Derrick Pitts would also be contributors.

[31] On June 20, Countdown debuted on Current TV, concluding with an abbreviated "Special Comment" in which Olbermann outlined his mission statement, quoting Harriet Beecher Stowe.

For the first two weeks of its Current TV run, Countdown ran slightly longer than an hour at sixty-three minutes in a covert effort to erode MSNBC's viewership.

However, Olbermann changed his mind and reverted the running time to the usual sixty minutes, realizing the move "would only serve to annoy fans of" both Countdown and Rachel Maddow's MSNBC show while doing nothing to improve the ratings for his own program.

Internal sources reported that Olbermann's repeated absences, his failure to promote Current TV, and disparaging public comments he had made about the network contributed to the decision to fire him.

[41] On April 3, 2012, Olbermann appeared on CBS's Late Show with David Letterman and voiced concern for his viewers and the production crew on Countdown, stating: "I screwed up.

Olbermann referred to production issues, in-fighting, and key absences during political events as the primary reasons Current TV decided to pull Countdown from the network lineup.

On a few occasions, during the show's MSNBC run, the segment was either briefly suspended or renamed in response to concerns that it contributed to an atmosphere of political divisiveness.

On October 7, 2020, Olbermann revived the "Worst Person in the World" branding for a current-events webseries, delivering an extended commentary on one selected individual (either Donald Trump or someone associated with his administration) followed by a brief rundown of other news headlines.

During the 2008 U.S. Presidential Primary season, Olbermann began using the term "Keith number" in reference to the sum of a pre-election opinion poll's margin of error and the percentage of respondents who are undecided.