When veteran political writer Paul Wells set out to write what he hoped would be the definitive portrait of Stephen Harper, he interviewed staffers in the Prime Minister’s Office, both current and past, as well as cabinet ministers and senior bureaucrats.

But there was one interview that eluded him: Harper himself.

"I spent about a year dealing with the Prime Minister's Office on the terms that would surround an actual interview with the guy," Wells told CTV's Canada AM Tuesday.

"I sent -- on more than one occasion -- my proposed questions for an interview, and in the end, they didn't even tell me there wasn't going to be an interview. In the end, there just wasn't an interview."

Wells wasn't altogether surprised the prime minister declined.

"Harper talks when he wants to talk, when he thinks it can help him. He was never sure about me, so he decided not to talk."

Even without Harper's input, Well says he enjoyed "excellent access" to many of the people who know the prime minister best. He says he was able to get a picture of why Harper became prime minister and how he's managed to hold onto power for so much longer than likely anyone ever expected.

The result is contained in a book called, "The Longer I'm Prime Minister."

Wells is a political columnist who's usually paid to offer his opinion of the goings-on on Parliament Hill, but he says for this book, he sought to simply craft a portrait.

"A lot of people are really grateful that someone like Stephen Harper is the prime minister today. And that comes as a surprise to a lot of other people who can't wait to see the back of the man. So for most of my book, I kind of keep my analytical head down," Wells explained.

"This is a history of Stephen Harper from the day after the 2006 election, to this spring. And it attempts to explain why he wins and why he wants to win."

The first chapter of the book is called 'Foot in the Door' because when Harper squeaked into power in 2006, a foot in the door is essentially all he had, says Wells. Harper had won the lowest share of seats of any prime minister -- a dozen fewer seats than Joe Clark, who lasted only nine months in power.

Since that first election win, Harper has worked fervently to keep a low profile, Wells writes, to avoid public gaffes and to control the messaging from his office. “The point of this word craft and image manipulation,” Wells writes, “is to last. The point of everything he does is to last.”

Wells also tried to secure an interview with Nigel Wright, Harper's former chief of staff, who stepped down amid the growing spending scandal involving Senator Mike Duffy. Wright also declined to be interviewed, but before he stepped down, he told the rest of senior PMO staff to speak with Wells to help him "get Harper's story right," the author reports.

After that, Ottawa became "suddenly kind of a chatty town," Wells says. Some had stories to tell about Harper's passion; others spoke about the fiery temper he displays behind closed doors. But nearly everyone Wells spoke to about Harper had a strong opinion to share, he says.

"I started to say that I feel a bit like a bellhop when I write about Stephen Harper because everyone brings so much baggage with them when it comes to discussion about him," Wells said with a smile. "Everyone has a strong opinion about Stephen Harper."

Now that the book is out, Wells has received no response from the PMO. But he says he's "gratified" by the early response so far.

"A very wide range of people think they see the Stephen Harper they know in there," Wells says.

"People say, 'Thank you for unmasking this charlatan.' And other people say, 'Thank you for explaining to Canadians why he's a great prime minister.' So I hope I've hit the sweet spot."