Members of the Queens Park Rangers board are reportedly opposed to the manager's drive to sign the 32-year-old.
Signing the experienced striker could see the floodgates open at Loftus Road and the goals fly in, keeping Redknapp's side in the Premier League and further enhancing his already glowing reputation as a master of the transfer market.
Should the deal go sour, however, the QPR boss will no doubt be blamed for another old, expensive signing that ultimately did nothing for his side.
Intriguingly, a recent report from the Daily Mirror suggests members of the R's board are opposed to Redknapp's interest in Defoe, with the striker being deemed too old for the west London side.
And the report makes sense. The same doubts were said to be harboured over Rio Ferdinand's signing and, so far, the doubters have been proven right.
That's why Redknapp has to play it smart with Defoe. He has said the right things publicly this morning - but caution is still needed. The politics of these things are more complicated than the manager often makes out during press conferences.
This is not necessarily about Redknapp's future, the 67-year-old getting the sack or anything like that.
But it is about the trust that is forged between a manager and his executives. QPR owner Tony Fernandes has spoken at length about how the club will change moving forward. No more expensive duds, no more unnecessary spending.
If Redknapp, however, plays hardball and pushes without compromise for the signing of Defoe, there will be tension at Loftus Road.
The pressure will then be on the 32-year-old striker to succeed at all costs, with Redknapp's reputation on the line. Once again, however, for the player, not that much will be at stake. Defoe would earn a good £90,000-a-week and know that he will continue to earn it if QPR go down (unless provisions are made to that end), with the forward's wages naturally providing a stumbling block for any potential sale.
It is a tricky path Redknapp is going down, then, if the QPR board do indeed hold reservations about signing Defoe. And it could cost him dearly if he doesn't play his cards right.