In what he called a "difficult decision," German Social Democratic (SPD) politician Martin Schulz announced on Thursday that he will not run for a third term as president of the European Parliament.

Instead, he intends to run to represent his home state of North Rhine-Westphalia (NRW) in the Bundestag - Germany's lower house of parliament.

Alluding to his efforts to increase the visibility and credibility of European policy, Schulz said on Thursday he had achieved a lot during his five years in office.

On leaving Brussels, however, the outgoing European Parliament president said he will remain closely linked to the European project, even if he's only able to do so from Berlin.

"I want to make a contribution in closing the gaps between countries," he told reporters.

Juncker 'disapponted'

Responding to the news on Thurday, President of the EU Commission Jean-Claude Juncker said he was "disappointed" at Schulz's departure from European politics. 

Juncker previously expressed his wish for Schulz to remain at the head of the European Parliament, even though the Social Democrat's term of office was actually due to end early next year.

Following an agreement with the conservative Christian Democrats, a politician from the faction of the European People's Party (EPP) is due to take over office for the second half of the legislature. Nevertheless, it had been speculated again and again whether there could be a back door route to enable Schulz to remain in the post.

Chancellor material?

Media speculation that Schulz could become the Social Democratic's candidate for chancellor in next year's German elections also meant that Schulz's move from Brussels to Berlin came as little surprise.

Speaking in the Belgian capital on Thursday, however, Schulz gave no further details on whether he might run as Merkel's rival.

Analysts have also said he could seek the post of foreign minister - a position that looks to be vacated by Frank-Walter Steinmeier, while Schulz's fellow SPD member is likely be chosen as Germany's next president.

Many supporters within the SPD believe Schulz's experience in the European arena would stand him in good stead for the role as foreign minister.

SPD Deputy Ralf Stegner said on Thursday that Schulz would be "a tremendous asset to the German Bundestag."

Scholz vs. Gabriel

After Merkel announced on Sunday that she would be running for a fourth term in office, all eyes are now on the SPD which is expected to confirm its candidate by the end of January.

A Social Democrat, through and through, Schulz previously told DW: "My favorite color is red. I belong to the reds, that is my life."

Should he be willing to take on the candidacy, however, Schulz might not be alone, with SPD leader and German Vice Chancellor Sigmar Gabriel also expected to throw his hat into the ring.

According to a poll published on Thursday, Schulz would have more chance than Gabriel of succeeding Merkel as chancellor next year.

Some 42 percent of participants said Schulz would be a promising opposition to Merkel, while 35 percent backed Gabriel. Among SPD supporters, results were clearer, with 54 percent favoring Schulz compared to the 41 percent behind Gabriel.

European career

Born in Hehlrath, close to the German-Dutch-Belgian borders, Schulz was set up from birth for a job at the helm of the European Union, at least geographically and linguistically. Fluent in German, Dutch and French, he also speaks English, Spanish and Italian - not to mention his Rhineland dialect.

After his dreams of becoming a professional footballer were quashed by a knee injury, Schulz turned to alcohol - an addiction he overcame with the help of his brother.

He began his political career at the age of 19 when he joined the SPD and within 12 years was elected NRW's youngest mayor - a post which he held for more than a decade.

But it was following Schulz's 1994 election as a member of the European Parliament that his political career really got off the group. Rising swiftly through the ranks in Brussels, Schulz became head of the German group of Social Democrats MEPs in 2000 and nine years later the chairman of the Social Democrats group in the European Parliament.

In January 2012, he was elected president of the European Parliament for a mandate of two and half years and went on in July 2014 to become the first president in the history of the European Parliament to be re-elected to a second term.

EU-skepticism on the increase

Armed with his European ideals, Schulz will now return to a Germany, which, like much of western Europe, is currently experiencing a rise in EU-skepticism and right-wing populism.

At the forefront of the anti-EU sentiment is Frauke Petry, leader of the right-wing populist party Alternative for Germany (AfD). Following Merkel's confirmed candidacy for the Chancellery on Sunday, Petry quipped that her party would ideally like to see Schulz as the SPD's top candidate - but only, she said, because he was responsible for the failure of the EU "like no other German."

Together, as the "dream duo of the grand coalition," Merkel and Schulz epitomize the demise of Germany, Petry said.

Schulz has expressed his dismay on countless occasions at the rise in Euroscepticism, not least of all the UK's shock Brexit result in June, which saw 52 percent of the electorate vote in favor of leaving the EU.

In his announcement on Thursday, Schulz described European integration as "the biggest civilization project of the past centuries."

Prior to the Union's existence, in the days of the First World War, Schulz's relatives would have been shooting at each other as they lived in different countries.

"We are often not aware of what we have inherited as a post-war generation," Schulz previously said. "I have lived a life in freedom with opportunities that my parents did not even dream of."