Progressives at last are noticing that the best argument for government activism is that it works.
( ( Progressives ( at last ) ) ( ( are ( noticing ( that ( ( ( the ( best argument ) ) ( for ( government activism ) ) ) ( is ( that ( it works ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Progressives)) (PP (IN at) (NP (JJ last)))) (VP (VBP are) (VP (VBG noticing) (SBAR (IN that) (S (NP (NP (DT the) (JJS best) (NN argument)) (PP (IN for) (NP (NN government) (NN activism)))) (VP (VBZ is) (SBAR (IN that) (S (NP (PRP it)) (VP (VBZ works))))))))) (. .)))
Progressives are arguing that government activism does not work whatsoever. 
( Progressives ( ( are ( arguing ( that ( ( government activism ) ( ( does not ) ( work whatsoever ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Progressives)) (VP (VBP are) (VP (VBG arguing) (SBAR (IN that) (S (NP (NN government) (NN activism)) (VP (VBZ does) (RB not) (VP (VB work) (ADVP (RB whatsoever)))))))) (. .)))