* Govt to outline possible defence cuts by end of year
* Italy cut F-35 order by 30 pct 2 years ago
* Defence investments reduced by 400 mln euros in 2014
ROME, May 7 (Reuters) - Lawmakers in Prime Minister Matteo Renzi's party on Wednesday backed cutting by half the 12 billion euros ($16.72 billion) earmarked for Italy's order of 90 Lockheed Martin F-35 fighter jets.
Parliamentarians from Renzi's centre-left Democratic Party (PD) in the lower house defence committee voted in support of the recommendation, which was made as part of a committee inquiry into overall defence spending.
While the vote by lawmakers in the centre-left Democratic Party (PD) does not bind the government in any way, it underlines the political pressure on Renzi to cut the programme as part of a broader squeeze on public spending.
With a mandate from the defence ministry, a working group of military and civilian specialists is reviewing military expenditure and has said it will present a document by the end of the year that outlines possible reductions.
Defence Minister Roberta Pinotti said on Wednesday the defence committee's recommendations would be among several elements considered during this review, but no decisions on cuts have been made.
Already this year defence investments are being cut by 400 million euros, including a 150 million-euro installment for the F-35 programme, to help fund promised tax cuts for 10 million low earners.
The PD document argues that the F-35 does not guarantee industrial gains for Italy and cites the repeated technical difficulties and cost overruns of the programme as reasons to reduce the order.
"This all means that there's a need for a moratorium to allow a renegotiation of the whole programme to clarify some difficulties and costs with the final objective of halving the original budget," read an excerpt from the 14-page document.
Italy cut its order for the radar-evading planes by 30 percent two years ago to stem state expenditure during the euro zone debt crisis.
Almost two-thirds of Italians view the F-35 as unnecessary, a poll showed in March, but it is supposed to replace the country's ageing fleet of fighter jets and further cuts could affect maintenance contracts held by the state-controlled defence group Finmeccanica. ($1 = 0.7177 Euros)
(Writing by Steve Scherer; editing by Andrew Roche)