The UK Unionist leader, Mr Robert McCartney, said his party would work positively in the new Assembly "but not at the price of dismantling the Union".
The party yesterday presented 13 candidates, two of whom will stand in Mr McCartney's North Down constituency.
"The United Kingdom Unionist Party will work positively and with commitment to achieve the best and most effective government for all the people but not at the price of dismantling the Union or accepting terrorist rule by proxy," said Mr McCartney. The deputy leader, Mr Cedric Wilson, will contest Strangford.
Mr McCartney said his party would enter the Assembly to defend unionist rights.
"The Assembly allows unionists to object to proposals in accordance with the mandate they give to those whom they democratically elected," he said.
Mr McCartney stressed his party would work to ensure "accountable government, free from the external interference of the Republic of Ireland" and "to seek the total assurance that the political representatives of terrorist groups who remain armed will be excluded from government".
The loyalist parties, the Progressive Unionist Party and the Ulster Democratic Party, also unveiled their electoral campaigns, saying the decommissioning issue would not discourage voters.
Twelve candidates will contest 11 constituencies for the PUP. They include Cllr Billy Hutchinson, recently nominated as the official liaison between two paramilitary groups, the Red Hand Commando and the Ulster Volunteer Force, and the International Body on Arms Decommissioning; Mr Hugh Smyth, former Belfast lord mayor; and a former Ulster Unionist councillor in Co Derry, Mr David Gilmour.
A former peace negotiator, Ms Dawn Purvis, the only woman PUP candidate, will stand with the party leader, Mr David Ervine, in Belfast East.
"We feel sure we can win two seats in East Belfast. Recent polls have shown that we have support and our own research backs that up," Ms Purvis said.
She doubted that loyalist paramilitary disarmament would have a negative effect for the PUP. She said: "We want to see the removal of all weapons, but we have to create conditions for that to come about, and the main condition for that is for the IRA to say the war is over."
Mr Ervine stressed the campaign would focus on issues such as health, housing and education.
"The essence of this election is taking responsibility on ourselves and controlling our daily lives. It is an opportunity for the return of daily democracy," he said.
In loyalist areas, particularly in Belfast, the PUP had worked successfully within the community to strengthen and broaden its base. "You can love us, you can hate us, but you cannot ignore us," said Mr Ervine, referring to increased support for the PUP.
The UDP, the political wing of the UDA and UFF, will field nine candidates.
The party leader, Mr Gary McMichael, will stand in Lagan Valley, while Mr David Adams, a Lisburn councillor, will contest South Belfast and a fellow party member, Mr John White, will stand in North Belfast.
"It is leadership that will influence people's decisions on whom they will select, and the UDP has shown leadership and that we are prepared to fight for the ordinary person throughout this process," Mr McMichael said.
Regarding paramilitary decommissioning, Mr Adams said the UDP had consistently supported the removal of "all illegal weapons in Northern Ireland, but we cannot do it on our own". Members of the loyalist community wanted to hear from the IRA that the war was over.