Given that current mainstream politics seemingly sees evaluating your own errors as some kind of a weakness, to openly do so right now would be fairly radical for a politician.
A radical is someone who is willing to use extreme measures to achieve their political objectives. Nothing to do with the status quo. Totalitarian regimes, for example, usually maintain their status quo with radical zeal and measures.
The Quakers are political radicals. They are so extreme they utterly refuse to kill people, even when ordered.
edit - Given the article about it also on the front page, I thought I'd look it up in the original Mirriam Webster. The result is kind of interesting;
>2. (Politics)
>One who advocates radical changes in government or social institutions, especially such changes as are intended to level class inequalities; -- opposed to conservative. In politics they [the Independents] were, to use phrase of their own time. "Root-and-Branch men," or, to use the kindred phrase of our own, Radicals. Macaulay.
http://lexicon.x10host.com/?w=radical
And to contrast with my first port of call, in the Cambridge dictionary you get a politically neutral definition;
>believing or expressing the belief that there should be great or extreme social or political change
> To typify a spectrum of radical views, we first conducted a separate online survey of 344 US participants (study 1) who completed questionnaires about political issues [4, 19, 20, 21, 22]. We included standard questionnaires about political orientation, voting behavior, attitudes toward specific political issues, intolerance of opposing political attitudes, belief rigidity, and (left- and right-wing) authoritarianism. These questionnaires were selected based on prior models of political radicalism as stemming from a combination of intolerance to others’ viewpoints, dogmatic and rigid beliefs, and authoritarianism, which represents adherence to in-group authorities and conventions, and aggression in relation to deviance from these norms [23, 24, 25]. However, we stress that radicalism is likely to reflect a general cognitive style that transcends the political domain—as exemplified by links between religious fundamentalism and increased dogmatism and authoritarianism [22, 26]—and instead refers to how one’s beliefs are held and acted upon [27].