。
The Prime Minister confronted his political rival's challenge head-on.
Literal
Prime-minister [subject-が] political-rival [attributive-の] challenge [with-と] head-on [from-から] confronted-[polite-ました].
Political news. 真っ向から ('head-on, directly, face-to-face') is a set adverbial phrase using 真っ向 ('head-on direction,' literally 'the true front') + から for the 'from' vantage. 対決する ('to confront, to face off with') takes と for the opposing party — showing that 'with' in English ('confront with') is structurally 'と' in Japanese. 政敵 ('political rival, political enemy') is a specific compound.