Adonis Georgiadis, a member of parliament (MP) for the Greek opposition party, New Democracy, told CNBC the reforms –based on higher taxation on businesses and the wealthy -- would "kill the economy" and should not be accepted by Greece's creditors, the so-called "troika" of the European Commission, European Central Bank (ECB) and International Monetary Fund (IMF).
"What he's trying to do is exchange reforms for more taxes and the troika should never accept something like that. The philosophy of the memorandum (Greece's bailout package) was to make our economy more competitive and be able to survive a loan in the real world but with all these taxes (proposed by Tsipras) will kill our economy," he said.
Speaking to CNBC in Athens, Georgiadis said that the higher taxation would prompt Greece's wealthy class to leave the country and would damage investment. "At the end of the day we'll have less money….they (Syriza) cannot put us in a program that will destroy the economy for ever."
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Georgiadis was formerly health minister under the New Democracy government, which had a track record for cooperating more fully with lenders demands until it was ousted in snap elections in January. He told CNBC that, although he didn't know if he would vote through the deal, he did not want to see Greece leave the euro zone – which could happen if the Greek parliament rejects the deal.
"Tsipras has put us in a very big dilemma," he warned.
Worrying for Tsipras, the proposals don't appear to have met with much more favor from within his own camp either. Syriza MP Costas Lapavitsas said that he was "deeply concerned" by the proposed reforms.
"I'm deeply troubled by what I read. It looks like we'll be imposing a lot of taxes and okay, there will be some re-distributive aspect to the taxes, but they are new taxes and are designed to make a primary surplus and they are recessionary measures."
He said he would "wait and see" what creditors said about reforms before deciding whether to approve the reform measures himself, or not. "I shall have to wait and see, I am skeptical about what the lenders say, I expected a hard response tomorrow (from lenders) and I expect new demands from them."
Asked whether the measures could tear his party apart, Lapavitsas said he was "very worried" about the party's future.
"If (the reforms) looks like this then I, and many other Syriza MPs, will have a lot of difficulty approving them…the Greek people voted us in because we opposed austerity and I'm very concerned about what this situation will do to our grass-roots support. There will be a lot of people who are very concerned and troubled about this situation."