The widespread opposition among Northern Ireland's 1 million Protestants to the recent Anglo-Irish agreement is hardening. Northern Ireland's Unionist members of the British Parliament, who favor retaining the link with Britain, have given notice that they will resign their seats in Parliament and seek reelection if the government does not grant the province's voters a referendum on the agreement.
Such a referendum is unlikely. The British and Irish parliaments are expected to formally approve the Anglo-Irish deal, signed Nov. 15, by the end of this week.
The Unionist politicians have massive Protestant support. Protestants oppose the agreement because they say that it was signed without consulting them, that it gives the Dublin government direct input to the control of Ulster (Northern Ireland), and that it is the first step toward Irish unity.
Meanwhile, a crowd of between 80,000 and 100,000 Protestants converged on Belfast's City Hall last Saturday in arguably the biggest political rally in Northern Ireland's history.
Flag-waving youths stood shoulder to shoulder with citizens of all ages who had traveled from every part of Northern Ireland to show their solidarity. Thousands wore sticker badges with the uncompromising message ``Ulster says no.''
The demonstration underlined that opposition to the agreement came from the widest spectrum of Protestant opinion. The physical presence of the demonstrators confirmed what some Protestant church leaders had been saying. The Presbyterian Church, the largest grouping in Northern Ireland, condemned the agreement outright. Presbyterian leaders dismissed it as ``a complete denial of open, democratic government.''
Such Protestant opposition accords with the latest public-opinion poll, published by the Sunday Times (London). It declared that 75 percent of Ulster Protestants would vote againt the agreement, if given a referendum, thus outvoting the 65 percent of Ulster's half-million Roman Catholics who, according to the poll, would accept it.
However, there is some comfort for both the British and Irish governments in that only 25 percent of Protestants would consider unconstitutional means to wreck the agreement.
At the moment, therefore, Protestant opposition to the agreement remains legal and constitutional. And leaders like James Molyneaux of the official Unionists, and the Rev. Ian Paisley of the hard-line Democratic Unionists, can argue that Saturday's massive rally shows that the Protestants mean business. Thousands cheered loudly as the two leaders, followed by 12 other Unionist members of Parliament, signed pledges to resign their seats.
Political confrontation between the Unionists and Mrs. Thatcher's government now seems the most likely pattern of the next few months. The Unionists are pledged to resign their seats by Jan. 1, and Northern Ireland seems destined to move into another year of uncertainty, despite the basic aims of the agreement which are to bring peace and greater understanding.