The surge in support for the UK Independence Party (Ukip) in parts of the country has put the issue of immigration squarely on the agenda during this election.
But it has not been without controversy.
Labour was slammed earlier this month for producing campaign mugs bearing the legend "Controls on immigration", a move the party said was designed merely to highlight one of its election pledges.
Nigel Farage also faced criticism when he spoke about HIV-positive foreigners being treated by the NHS during one of the televised leaders' debates.
Many parties have tried to move the political agenda away from immigration to concentrate on the NHS or the economy instead.
But it cannot be denied that migration is an issue in this General Election.
Here we look at the main policies set out by the parties:
Conservatives
The Tories have downgraded their target to cut net migration to below 100,000 to merely an "ambition", after recent figures showed the number was closer to 300,000.
The party also wants to cap skilled migration from outside the EU at just over 20,000.
To try to reduce what it says are "pull factors" that bring people to the UK it would also scrap child benefit for dependants living outside the country, create a four year residency requirement for EU migrants to claim social housing and tax credits and negotiate to reform EU freedom of movement rules. Migrants who fail to find a job after six months would have to leave the UK.
Labour
Labour wants to hire 1,000 new border staff and introduce 'proper' exit checks to count the number of people leaving as well as entering the UK.
The party would also make it illegal for employers to undercut British workers' wages by exploiting migrants and ensure that public sector workers, including nurses and doctors in the NHS, can speak English.
Labour also wants to introduce a two-year wait before EU migrants can claim out-of-work benefits.
SNP
The party says that it will support "sensible immigration policies" that help to meet Scotland's economic needs.
The SNP also wants to re-introduce post-study work visas, to allow students educated in Scotland to work in the country for two years after their graduate.
Lib Dems
The Liberal Democrats say that they would restore full entry and exit border checks on people coming to and leaving the UK.
The party also says that it would end indefinite detention for immigration purposes.
On the issue of child benefit, the Lib Dems want to phase out payments for offspring who live abroad.
The party also wants new claimants with poor English skills to attend language courses in order to receive jobseekers allowance.
Ukip
One of the main reasons Nigel Farage's eurosceptics want to leave the European Union is that it says this will allow the UK to "take back" control over its borders.
Ukip also wants to introduce an Australian-style points-based immigration system, which the party thinks would reduce net migration to the tens of thousands.
The party also wants to end free access to the NHS for new immigrants until they have paid into the system for five years.
Greens
The Greens do not believe that there should be a numerical cap on net migration of the kind that some of the other parties are suggesting.
The party would also scrap the current Coalition Government policy that means a British citizen has to have an income of at least £18,600 a year before their partner can come to live in the UK.
They would also introduce more rights for illegal immigrants who have been in the UK for three years.
DUP
The DUP says the UK needs to build a "national consensus" on immigration.
The Northern Irish party says that this would reflect the value of immigrants to the UK, but also impact on local communities.
A limit on the numbers coming to the UK can help to "reduce tensions" it says.
Among its calls are for stronger border controls. a recognition of the contribution of immigrants., support for local communities to help integrate those from abroad. a requirement that people must contribute to our country before they can access benefits and services and a joined up immigration and Integration service.
Plaid Cymru
The party wants to create a 'Welsh Migration Service' which would involve drawling up a list of skills shortages to help ensure migration meets Welsh needs.
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