Two heavy hitters in the UK Labour Party sought to position themselves to challenge Prime Minister Keir Starmer on Thursday, albeit with neither announcing a direct challenge, instead seeming to encourage the embattled party leader to make way voluntarily.  Health Secretary Wes Streeting made the most direct move, becoming the first senior member of Starmer's Cabinet to resign in protest after Labour's drubbing in local and regional elections last week .  But former party deputy leader Angela Rayner also issued a crack-of-dawn alert to the press saying that the tax scandal that prompted her resignation was now resolved, in what was interpreted as an oblique statement of intent. A combative Starmer speech on Monday and a tense Cabinet meeting on Tuesday both failed to calm the waters after the election losses.…