Under Williams' plan, churches that agree to the as-yet-unwritten covenant would be "constituent" churches, while those that don't would be "churches in association," he said in a letter to the top bishops in each of the communion's 38 provinces.
The Episcopal Church, with 2.2 million members, is the U.S. branch of the 77 million-member Anglican Communion.
"There is no way the Anglican Communion can remain unchanged by what is happening at the moment," Williams said.
The archbishop's statement comes amid a tumultuous summer for the Episcopal Church and more conservative sister churches who have lost patience with the Americans' liberal stances.
Though the outlines of the plan remain sketchy, it seems to raise the possibility that the Episcopal Church could be pushed to the margins of Anglican life if it continues its independent-minded course on matters of human sexuality.
One of the largest U.S. parishes, Christ Church Episcopal in Plano, Texas, said Monday it plans to disassociate from the national church "as soon as possible." With an average of 2,200 Sunday worshippers, the church's size rivals some dioceses, including Nevada, whose bishop, Katharine Jefferts Schori, was recently elected the denomination's next presiding bishop.
In the neighboring Episcopal Diocese of Fort Worth, Bishop Jack Iker has asked to place his flock under the oversight of a foreign primate because he does not accept Jefferts Schori's leadership. Fort Worth is one of three U.S. dioceses, including San Joaquin, Calif., and Quincy, Ill., that does not ordain women as priests.
Williams said recent events have made clear the Communion "lacks a set of adequately developed structures with which to cope with the diversity of views that will inevitably arise in a world of rapid global communication and huge cultural variety."
While the ordination of women continues to be a source of tension in the Communion, particularly among conservative "Global South" churches, the "trigger for much of the present conflict" was the consecration of an openly gay man as bishop of New Hampshire in 2003, Williams said.
Though the consecration of Bishop V. Gene Robinson was hailed by many Episcopalians as a breakthrough for gay rights, conservative Anglicans bashed the American church's perceived abandonment of Scripture and tradition.
As archbishop of Canterbury, the fount of the original Church of England from which the Anglican Communion springs, many look to Williams to solve divisive problems. Though he lacks the power of a pope, the archbishop holds great moral sway within the church.
"Rowan has a way of standing above it all and trying to connect everything," said the Rev. Kendall Harmon, a conservative theologian from South Carolina.
The "best way" to connect Anglicans at this time would be a shared covenant among Communion churches, Williams said.
In the archbishop's proposal, national churches that signed the covenant "as an expression of their responsibility to each other," would be "constituent churches" and full members of the Communion.
Those choosing not to opt in, which the archbishop called "churches in association," would become "observers," with no power to make decisions in the Anglican Communion. Williams likened the association of churches to the Methodist Church, which rose out of the Church of England but later became autonomous.
Williams' solution is no quick fix, church experts say. Several predicted that a covenant could not be drawn up before 2009.
At their General Convention earlier this month, Episcopalians approved a resolution that "supports the process for developing" an Anglican covenant "that underscores our unity in faith, order and common life." But delegates were wary about supporting any particular covenant at this time, said the Rev. Tobias Haller, a church delegate and rector of St. James Church in the Bronx, N.Y.
In 2004, Anglican leaders put forth a possible covenant but it was roundly panned.
It remains to be seen how the archbishop's proposal would affect dissident churches within the Episcopal Church.
Bishop Robert Duncan of Pittsburgh said in a statement Tuesday, "Finally, the archbishop understands that the fault lines in the Communion run not only between provinces but through them and that there may well be a need within provinces for an `ordered and mutually respectful separation."'
Duncan is chief moderator of the Anglican Communion Network, a conservative group of 10 dioceses and some 800 parishes that has threatened to leave the Episcopal Church.
"We need ways of translating this underlying sacramental communion into a more effective institutional reality, so we don't compromise or embarrass each other in ways that get in the way of our local and our universal mission, but learn how to share responsibility," Williams said.