Beatrix von Storch, MEP for Alternative for Germany party speaks at a rally in the city center on November 6, 2015 in Berlin, Germany | Carsten Koall/Getty Images Far-right MEPs make the case for staying in ECR group Two MEPs threatened with expulsion tell parliamentary group it will be much stronger with them as members.

Two Alternative for Germany MEPs who were threatened with expulsion from the European Conservatives and Reformists group in the European Parliament believe their futures are safe in the wake of German regional elections on Sunday.

In an email sent to all ECR MEPs and seen by POLITICO, the AfD's Beatrix Von Storch and Marcus Pretzell reminded their parliamentary colleagues of the far-right party's election successes. The AfD made significant inroads in all three states that voted last weekend. In Saxony-Anhalt, it emerged as the second-largest party with 24 percent of the votes and now has representation in half of all German states.

The mail also takes a pop at former AfD leader Bernd Lucke, who left to form his own party, Alfa, whose MEPs are also part of the ECR group and which did badly in the regional elections.

“Alfa ... most notably our colleagues [Hans-Olaf] Henkel and Lucke, have mobilized their friends and family — with even ECR staff having to run for office — for [...] on average, 0.8% of the votes, gaining no seats at all,” the AfD pair wrote.

“The contrast between the success of the AfD and Alfa's failure could not be bigger. In this context, we cannot help but doubt the group leadership's decision to succumb to Alfa's threat that if the AfD stays with the ECR, they will leave the group,” said the mail.

"We do not think it prudent of the leadership to allow some delegations to use the ECR as a tool for political warfare with their national opponents. Leadership should be strong enough to resist such pressure.”

Earlier this month, the ECR's leadership asked the AfD to leave the group before March 31, otherwise a motion would be tabled to expel them at a meeting on April 12. According to sources, the ECR move was prompted by comments made by von Storch and party leader Frauke Petry about shooting refugees.

Von Storch has contested the ECR's decision, saying: “There was no majority to vote for the exclusion of the AfD. It was a compromise ... to avoid losing face. We remain full members of the European Parliament.”