The chair of the Foreign Affairs Committee vowed to be "a voice for the membership, unions, PLP, and our constituents - not just nod along" if she is elected deputy Labour leader on 25 October.
Candidates have until 5pm on Thursday to win the support of at least 80 fellow Labour MPs to proceed to the next stage in the deputy leadership contest.
The newly-released files were handed over following a demand by the Oversight Committee of the US Congress, and appear to contain notes to the billionaire paedophile from Donald Trump and Peter Mandelson.
Israel has strongly denied that its actions in Gaza amount to genocide, but is being challenged on the issue in a case at the International Court of Justice in The Hague.
Bell Ribeiro-Addy has been backed by left-wing colleagues, but more candidates could come forward over the coming days. Meanwhile, the prime minister is assembling his cabinet for the first time since last week's reshuffle.