Tom Elliott Ulster Unionist leader Tom Elliott has rejected the idea
The Conservative Party chairman has written to the Ulster Unionist party suggesting they disband and a new Conservative-led party is formed.
The offer is contained in a letter to the Ulster Unionist Party leader Tom Elliott.
Mr Elliott said there is no question of the party being dissolved.
The two parties formed an electoral alliance and fielded joint candidates in the general election but failed to gain a single MP.
The letter was sent by Conservative Party chairman Lord Feldman to UUP Leader Tom Elliot.
Lord Feldman states that the UUP would be dissolved early next year and would be replaced by a Conservative-led party which would operate along the lines of the parties in Scotland and Wales.
It is understood the idea has the backing of the Prime Minister David Cameron, the board of the Conservative Party, as well as the chairman of the Northern Ireland Conservative Party.
But Mr Elliott called a full merger "unacceptable".
"There is no question of the Ulster Unionist Party being dissolved," he said.
"As indicated at our recent party conference, the party is planning significant research throughout Northern Ireland to test opinion on a number of issues, including any potential future relationships with the Conservatives.
"Any further development needs to be based on evidence that the electorate will respond favourably, and that we are able to start to mobilise unionist voters who have decided not to vote for any party in recent elections. I would not contemplate taking any significant decisions without such research."
The Ulster Unionist leader also said that he hoped to meet with the Conservatives soon.
In a statement, the Conservatives said: "The Conservative Party has a long standing relationship with the Ulster Unionist Party.
"As part of our continued commitment to bringing mainstream Westminster politics to Northern Ireland, we have made a broad, generous offer to the Ulster Unionist Party to join forces with the Conservatives."
The party formed an alliance with the Ulster Unionist Party in 2008 and put forward joint candidates in the European and general election.
Candidates stood under the banner, Ulster Conservative and Unionist New Force (UCUNF).
Resignation
No UCUNF candidate was elected in the 2010 general election.
The pact was also damaged when the UUP's only MP, Lady Sylvia Hermon resigned from the party before the general election.
She was re-elected as the Independent MP for North Down.
A review followed and while relations remain friendly, separate candidates were fielded in the local government elections.
It was agreed that if elected, Conservatives and Ulster Unionists will cooperate on councils.
The chairman of the Conservative Party in Northern Ireland, Irwin Armstrong, resigned in December when he learned that the party had decided not to field candidates in the Stormont elections, complaining of a lack of consultation.
He announced in February that he would remain in his post despite tendering his earlier resignation.
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