March of the Migrant Voter? Kind of...

The headline on the front page of the Daily Mail is, perhaps unsurprisingly, a little over the top.

The source is a report, published by the Migrant Rights Network, on the growing importance of voters born in other countries.

Almost 4-million will be entitled to vote in May, people who've either come from Commonwealth countries, or been given British citizenship after 5 years' residence.

The report points out this group is bigger than the total number planning to vote for UKIP, yet says they're being largely ignored by mainstream parties.

And it warns that what it calls "anti-immigrant rhetoric" from some politicians runs the risk of alienating millions of voters.

The two seats that have the Mail so excited are Brent North and East Ham -- both safe Labour territory.

But there are plenty of other seats where the growing migrant vote, coupled with a greater mix of minority ethnic groups, will be a key factor in May.

In London, this includes seats held by all three main parties, and a handful of Conservative seats Labour hopes to seize.

On paper, this is good news for Labour. Another report highlights the party's share of the vote among minority groups is more than double the average -- 68% at the 2010 election, against 29% overall.

But the party's being pulled in two directions. In the north of England, UKIP's eating into natural Labour territory. That's pushing Ed Miliband into talking tough on immigration.

But that could alienate minority support for Labour -- hugely important to the party's prospects in London and elsewhere.

Researchers say when minority voters defect from Labour, they tend not to switch to another party -- instead they often don't vote at all, making Labour's job that much harder.

There are lessons too for the Conservatives. As minority communities grow, the party's struggle to engage those groups is becoming a real headache. 

Polling by Lord Ashcroft concluded the "biggest single predictor of not voting Conservative is not being white" -- in 2010 just 16% of the non-white vote went to the Tories.

It can be done. Canada's conservative prime minister Stephen Harper more than tripled minority support for his party in a decade.

Migrant voters may not be "on the march" -- but any party that ignores them is taking a big risk.