Sir Jeffrey Donaldson, who has announced his DUP leadership bid, is currently the party’s leader at Westminster.
He holds the title of the longest-serving MP from Northern Ireland and has been walking the halls of Westminster during various periods since 1997.
His decision to run for party leader has sparked an open contest for the role for the first time in the party’s history since it was founded in 1971.
The 58-year-old, who was born in Kilkeel in Co Down, first started out with the Ulster Unionist Party (UUP), which he joined at a young age.
Sir Jeffrey has previously spoken about the first time the Troubles visited his family following the murder of his cousin Samuel Donaldson, an RUC constable.
He was the first policeman to be blown up by the IRA in the conflict.
It was this event that influenced Sir Jeffrey’s decision to enter political life.
At the age of 16, he followed his family tradition by becoming a member of the Orange Order, and later followed in the footsteps of his late father Jim by joining the Ulster Defence Regiment (UDR).
The former Ulster Unionist is seen as a moderate whose political outlook would be broadly in line with Arlene Foster’s.
In 1985, aged 22, he was elected to the Northern Ireland Assembly, becoming the youngest person to win a seat at Stormont.
His relationship with former UUP leader David Trimble began to crumble over the Good Friday Agreement.
Sir Jeffrey led a walkout of the 1998 peace talks after opposing the early release of republican and loyalist prisoners.
He left the party along with Mrs Foster and Norah Beare and joined the DUP in January 2004.
There is a sense that the traditional wing of the DUP never quite trusted Mrs Foster due to her UUP roots, and Sir Jeffrey could face a similar challenge if he was to succeed her.
In 2009, Sir Jeffrey 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, Sir Jeffrey denied the movies he watched were of an adult nature.
Asked what films he was watching, Sir Jeffrey said they included the Star Wars trilogy and The Lion, The Witch And The Wardrobe.
He was recognised by the Queen in her 2016 Birthday Honours and was given a knighthood.