SIR Jeffrey Donaldson has become the new DUP leader today taking the helm of a fractious and bitterly divided unionist party. 

The Lagan Valley MP takes up his post just weeks after he was defeated by 19 votes to 17 by Edwin Poots in the party leadership election to succeed Arlene Foster. 

During last month's DUP leadership contest - which followed Foster's ousting - he pitched himself against the creationist Poots (below) as the more moderate of the two candidates.

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However by the standards of most people, Donaldson is far from being a moderate.

The 58-year-old, who was born in Kilkeel in Co Down, first started out with the DUP's rivals, the Ulster Unionist Party (UUP), which he joined at a young age.

His decision is believed to have been prompted by the murder of his cousin Samuel Donaldson, an RUC constable, who was the first policeman to be blown up by the IRA in the conflict.

Donaldson became constituency agent for the far right South Down MP Enoch Powell in the mid-1980s before working as a personal assistant to the former Ulster Unionist Party (UUP) leader James Molyneaux.

In 1985, aged 22, he was elected to the Northern Ireland Assembly, becoming the youngest person to win a seat at Stormont.

Twelve years later after Lord Molyneaux retired as an MP in 1997, Donaldson was voted as his successor as MP for Lagan Valley, retaining the seat through six subsequent elections.

He now holds the title of the longest-serving MP from Northern Ireland.

READ MORE: Sir Jeffrey Donaldson becomes new DUP leader

His relationship with UUP and its former leader David Trimble (now Lord Trimble) began to crumble over the Good Friday Agreement signed in 1998.

Trimble backed the deal which helped bring about the end of the Troubles, which had lasted more than three decades and left more than 3000 people dead.

Donaldson led a walkout of the 1998 peace talks after opposing the early release of republican and loyalist prisoners and was a thorn in party leader Trimble's side until he eventually defected to the more hardline DUP.

He joined the DUP - along with Foster who also opposed the Good Friday Agreement - in January 2004.

He was appointed to the Privy Council, a body which advises the monarchy, in 2007 and stood down as an MLA for Lagan Valley in 2010.

He's also hit the headlines for scandal. In 2009, Donaldson apologised for claiming for pay-to-view movies on his parliamentary expenses during hotel stays.

He repaid the £555 and said he was wrong to submit the claims.

While the cost of the films was in the highest price category, Donaldson denied the movies he watched were of an adult nature.

Asked what films he was watching, he said they included the Star Wars trilogy and The Lion, The Witch And The Wardrobe.

READ MORE: Edwin Poots resigns as DUP leader after just 21 days in role

Donaldson was recognised by the Queen in her 2016 Birthday Honours and was given a knighthood.

As the new DUP leader he faces many acute political challenges.

He will have to reach an agreement with Sinn Fein if the DUP are to continue to govern with the republican party in the power sharing arrangement in Belfast.

And he must decide what to do regarding the Northern Ireland protocol in the Brexit agreement - the unpopularity of which among hardline Unionists helped bring down Foster just weeks ago.

Top of his immediate list though is that - unlike Poots - he does want to be First Minister in Stormont.

However, the position can only be occupied by a MLA as he currently only sits in Westminster.

He must then find a seat in the Assembly. 

Commentators in Northern Ireland believe this may not be too difficult with a compliant DUP member with a safe seat being 'given a tap on the shoulder' and asked to quietly go to make way for Donaldson.

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However, what may be more of a political challenge for the new leader is keeping the Lagan Valley constituency for the DUP in a by-election while a civil war rages within his party.

Veteran Irish journalist Eamonn Maillie raised the prospect of the talented and high profile councillor Sorcha Eastwood - of the Alliance Party which is no unionist) taking Donaldson's Westminster seat.

Maillie noted a couple of days ago on Twitter: "DUPLeader…if ⁦@J_Donaldson_MP⁩ wants to be FM and no vacancy obtains in the Assembly a sitting DUP member might get ‘a tap on shoulder’ & be told “take a hike.” FM means Jeffrey stepping down as Lagan V MP. Could ⁦@SorchaEastwood⁩ take Lagan Valley in by-election?" 

The next few weeks will tell us whether Donaldson can draw a line under the turmoil raging in the DUP just as the Orange marching season gets underway in Northern Ireland.