Nearly 200 MPs, including the leaders of both main opposition parties, have backed calls for nurses to get a full 2.5% pay increase this year.
Nurses say their pay rise is being devalued
Nurses in England, Wales and Northern Ireland have been offered a 1.5% rise followed by another 1% in November.
The government says this is affordable but nurses want the 2.5% immediately and are being balloted over whether they want a vote on industrial action.
David Cameron and Sir Menzies Campbell are among MPs who have backed the call.
The Royal College of Nursing (RCN) ballot will ask its 300,000 NHS members whether they would support a vote on what would be the first ever national industrial action.
An emergency motion was passed unanimously at the RCN conference in April calling on the government to implement the full 2.5% pay rise as recommended by the independent pay review body.
Under the staged pay-rise plan, nurses are being given a 1.5% pay rise from April this year followed by further 1% rise seven months later.
The RCN claims the pay award is the equivalent of a below-inflation 1.9% pay rise and is saving the government £60m.
At the annual conference, RCN general secretary Dr Peter Carter revealed plans to write to MPs to canvass opinions on the issue of nurses' pay.
In total, 186 MPs have either written to the RCN to express their support or signed Early Day Motions calling for the full 2.5% pay rise for nurses.
They include several leading Labour figures - the deputy leadership candidate Jon Cruddas, former health secretary Frank Dobson and former ministers Kate Hoey and Stephen Byers.
Conservative leader David Cameron, shadow health secretary Andrew Lansley, Northern Ireland's First Minister Ian Paisley, Liberal Democrat leader Sir Menzies Campbell and his predecessor Charles Kennedy have also backed the calls.
Dr Carter said nurses "spoke with one voice" that the government's staged pay deal was "unjust, undeserved and unacceptable".
He added: "It is clear from the response we have received so far that many MPs of all political persuasions also believe the government is just plain wrong on this issue."
On Saturday the Royal College of Midwives voted unanimously to consider a ballot for industrial action for the first time in their history over the staged 2.5% pay rise.
Strike rule change
Karen Jennings, head of health at public services trade union Unison, said the cross-party backing from MPs showed they felt nurses were "being short-changed".
She added: "There is still time for the government to think again and prevent the growing reality of industrial action in the NHS."
Historically nurses have not been allowed to take industrial action but a rule change in the mid-1990s permitted measures which do not harm patient care.
This means an all-out strike would be highly unlikely but it does allow nurses to take other steps such as refusing to do overtime.
The government has said its pay offer was a sensible increase that was fair for NHS staff and affordable for the economy.
A spokesman for the Department of Health said: "Clearly, any ballot for industrial action is a matter for the RCN, but the government is maintaining a dialogue with them and other unions to seek a resolution following the 2007/8 pay award."
Average pay has increased from £12,000 for a basic grade nurse in 1997 to £20,000 today. Average pay for all nurses has also increased at a similar rate to £25,000.