Labor MPs are closely monitoring the performance of Bill Shorten, with the Opposition Leader's pending appearance before the trade union royal commission and a series of Fairfax Media reports on deals the former Australian Workers Union leader struck making some nervous.

The federal ALP's decision to block the government's changes to the pensions asset test - which opened the way to a Coalition-Greens deal to save $2.4 billion and left Labor isolated - and a drop in Mr Shorten's personal standing in the Fairfax Ipsos poll this week has also caused jitters among some in the caucus.

Fairfax Media revealed on Wednesday that Mr Shorten's old union was paid nearly $300,000 after he struck a workplace deal that cut conditions and saved the company, Thiess John Holland, as much as $100 million on the $2.5 billion East Link tollway in Melbourne, back in 2005. It was one of a series of controversial deals struck on Mr Shorten's watch.