* Finance minister English announces plan to run for leadership
* Contenders line up after PM Key's shock resignation
* English the front-runner in a growing field (Adds political analyst quotes, paragraphs 4, 10-11)
By Swati Pandey and Charlotte Greenfield
WELLINGTON, Dec 6 (Reuters) - At least three senior ministers joined the race to replace New Zealand Prime Minister John Key on Tuesday, a day after Key stunned the nation by resigning to spend more time with his family, with his deputy Bill English seen as the front-runner.
English, the finance minister and deputy leader of the ruling centre-right National Party, announced his candidacy, as did Health Minister Jonathan Coleman and Police Minister Judith Collins. Other contenders may yet still emerge before the party holds a caucus meeting on Monday to vote for a new leader.
English, who has been endorsed by Key, is seen as best-placed to win but some analysts felt Coleman stood a chance.
"It's Bill English's to lose in the sense that there's such a strong endorsement and essentially direction from Key that it's very difficult for the caucus to outright repudiate the prime minister's preference," said Jon Johansson, a political scientist at Wellington's Victoria University.
Several Cabinet members, including Immigration Minister Michael Woodhouse and Primary Industry Minister Nathan Guy, have declared their support for English.
Other potential candidates include senior Cabinet minister Steven Joyce, fellow Cabinet minister Paula Bennett and Energy Minister Simon Bridges.
"I can see fantastic opportunities for stronger economic performance, for spreading the benefits of growth for more New Zealanders ... I am a candidate for leadership," English told reporters after a caucus meeting in New Zealand's distinctive "Beehive" parliament building in the capital, Wellington.
National elections are not expected until late 2017.
A recent UMR survey of voters pegged English as favourite to replace Key on 21 percent, followed by Joyce on 16 percent, Bennett on 11 percent and Collins on 6 percent. Coleman was not ranked in the survey, which was conducted in early October, but said he had youth and energy on his side.
Johansson said some backbenchers felt senior party positions were all held by old hands and there was room for new blood.
"I think there could be a little bit more turbulence going on in that caucus than surface appearances," he said.
Key has been New Zealand's leader since 2008 and the National Party is part-way through a third, three-year term that has been marked by political stability and economic reform. remains one of the world's most popular leaders, praised for his stewardship of New Zealand's $170 billion economy in the aftermath of the global financial crisis and two devastating earthquakes in Christchurch, the largest city on New Zealand's South Island. (Writing by Jane Wardell; Editing by Paul Tait)