Sentence:  Fianna Fáil lost the 1948 general election to Fine Gael (as Cumann na Gael were now known), who proceeded to <WSD>gazump</WSD> the Republican credentials by leaving the British Commonwealth and officially declaring the Free State a republic. 
Meaning of the word marked with <WSD> tags:  To trump or preempt; to reap the benefit underhandedly from a situation that someone else has worked to create.