A new tool was applied to social media following the presidential debate, and it showed that public sentiment was Obama won on substance, whereas Romney appeared to win by lying. The ability of social media to spread the word about fact-checks has changed the game.

NBC used a tool called ForSight, used to gauge public opinion in new media, to conclude that by Friday there was a sustained social media backlash against the punditry calling the Denver presidential debate for Romney. The new meme was that if Romney “won”, he did so by lying, whereas Obama had won on substance.

The immediate consensus that Mitt Romney won Wednesday’s presidential debate has eroded significantly as fact-checkers have weighed in and supporters of President Barack Obama have fought back, according to NBCPolitics’ computer-assisted analysis of more than 1.3 million post-debate comments on social media.

The analysis suggests that as debate over a news event continues unmediated over time, the impact of the conventional wisdom of journalists and partisan commentators can be mitigated…

By Friday morning, the counterargument that Obama had actually won on substance had taken root, with online sentiment now favoring the president.

I am not presenting these revelations to argue that Obama won the debate. It was established by the media that Romney won the debate, even if this study — based upon the post mortem fact-checking that damaged Romney’s “win” — says otherwise. Romney has also gotten a small bounce in post debate polls so far among undecideds.