Angela Merkel could be ousted as Chancellor by next week if she doesn't come up with a plan for the migrant crisis, a German MP claims.

Kai Whittaker, a member of Ms Merkel's Christian Democratic Union, said infighting could weaken the ruling coalition and make her position untenable.

Ms Merkel is at war with her Interior Minister Horst Seehofer, who wants Germany to send back migrants who have registered in other EU countries.

Angela Merkel could be ousted as Chancellor by next week if she doesn't come up with a plan for the migrant crisis, a German MP claims

Standoff: Merkel is rowing with Interior Minister Horst Seehofer (pictured together) over his plans to send back migrants who have registered in other European Union countries

A reversal of her 2015 open-door migrant policy would be a huge blow to her authority, with neither of the pair willing to back down.

'We are in a serious situation because the question of the migration crisis evolved into a power question,' Mr Whittaker, 33, told BBC radio.

'The question is who is leading the government? Is it Angela Merkel or is it Horst Seehofer? Everybody seems to be standing firm and that's the problem.'

The MP for Rastatt in Baden-Württemberg said parliament was confused about what the coalition's migrant policy even was.

'We don't know really. There is a master plan to solve the migration crisis, which consists of 63 ideas of Horst Seehofer,' he said.

'We don't know that concept yet, so we are a bit in the blue.'

Kai Whittaker (pictured with his sister Leigh), a member of Ms Merkel's Christian Democratic Union, said infighting could weaken the ruling coalition and make her position untenable

Merkel wants two weeks to try to strike bilateral deals with partners, such as Italy and Greece, on migrants and to make progress at an EU summit on June 28-29 on an EU-wide policy.

However, Mr Whittaker said the party needed to sort out its plan quickly well ahead of Bavarian state elections on October 14.

The Christian Social Union, led by Mr Seehofer, is facing an uphill battle to win a majority and doesn't want to wait.

'It is vital for the CSU to win an overall majority because that's why they have a national importance,' Mr Whittaker said.

'This kind of has the potential to diminish the authority of her and Horts Seehofer and it could well be that at the end of next week we have a new situation.'

When asked what he meant by a new situation, Mr Whittaker clarified that he meant 'probably a new Chancellor'.

'I can't say it's out of the question,' he added.

Merkel's refugee policy has led to more than 1.6 million migrants arriving in Germany in the last three years

Merkel (pictured with Trump at G7) is sticking to her guns, maintaining an open-door migrant policy is crucial for keeping Europe united

Ms Merkel is sticking to her guns, maintaining an open-door migrant policy is crucial for keeping Europe united despite the political standoff with her Bavarian ally.

In her weekly podcast, three days before talks between Ms Merkel and French President Emmanuel Macron outside Berlin, she hammered home her stance.

'This is a European challenge that also needs a European solution. And I view this issue as decisive for keeping Europe together,' she said.

Members said Mr Seehofer would defy Merkel on Monday if no compromise has been reached by then, and go ahead with the plans alone.

Such an affront to Merkel could force her to fire Seehofer, and there is even talk of the end of the 70-year conservative parliamentary alliance between the two parties.

Without the CSU, the CDU and Social Democrats, the third party in her 'grand coalition', would lack a majority.

Members said Mr Seehofer would defy Merkel on Monday if no compromise has been reached by then, and go ahead with the plans alone

A reversal of her 2015 open-door migrant policy would be a huge blow to Merkel's authority

Last week, Merkel confronted the risk of losing the full support of her own CDU, many of whom support the CSU's tougher line.

But she won over a majority of her lawmakers on Thursday and most are now behind her.

Merkel's refugee policy, which led to more than 1.6 million migrants arriving in Germany in the last three years, is widely blamed for a surge in support for the far-right Alternative for Germany (AfD),

The party entered parliament after a September election and became the main opposition party.

In her podcast, Merkel also said Germany and France, the EU's strongest axis despite some differences, would try to give new momentum to European cooperation on foreign, defence and security policy to contribute to a strong and unified Europe.

She also said the partners would work on further developing the economic and currency union and innovation.