(Rome) The Archbishop of Canterbury sought Thursday to downplay the implications of the Vatican’s unprecedented invitation for Anglicans to join the Catholic Church as he arrived in Rome for his first talks with the pope on the new policy.

The Vatican has said it was merely responding to the many Anglican requests to join the Catholic Church and has denied it was poaching for converts in the Anglican pond.

But the move has already strained Catholic-Anglican relations and is sure to affect Williams’ 77-million worldwide Anglican Communion, which was already on the verge of schism over homosexuality and women’s ordination issues before the Vatican intervened.

In a speech at the Pontifical Gregorian University in Rome, Williams was gracious in referring to the Vatican’s new policy, which he called the “elephant in the room.” The policy was an “imaginative pastoral response” to requests by some Anglicans but broke no new doctrinal ground, Williams said.

He spent the bulk of his speech describing the progress that had been achieved so far in decades of Vatican-Anglican ecumenical talks and questioning whether the outstanding issues were really all that great.

“The ecumenical glass is genuinely half full,” the archbishop said.

Anglicans split from Rome in 1534 when English King Henry VIII was refused a marriage annulment. For decades, the two churches have held theological discussions on trying to reunite, part of the Vatican’s broader, long-term ecumenical effort to unify all Christians.

But differences remain and the ecumenical talks were going nowhere as divisions mounted between liberals and traditionalists within the Anglican Communion itself.

While acknowleging the outstanding differences with Rome, Williams suggested that a way forward might be to embrace a “diversity of types of communion,” in which communion could be achieved but not with a “single juridically united body.”

The Vatican official in charge of relations with Anglicans, Cardinal Walter Kasper, also sought to put a positive interpretation on the future, drawing a clear distinction between the doctrinal talks on unification and questions of conversion.

“We cannot close our doors when others knock on them. But this does not exonerate us from” pursuing the broader unification of the churches as institutions, he said in a speech to the Gregorian symposium.

The new policy allows Anglicans to convert to Catholicism but retain many of their Anglican liturgical traditions, including married priests. The Vatican will create the equivalent of new dioceses, so-called personal ordinariates, for these former Anglicans that will be headed by a former Anglican priest or bishop.

Estimates on the number of possible converts has ranged from a few hundred to thousands.

The new policy has elicited heated criticism in Britain, both in Anglican and Roman Catholic circles. Catholic theologian Nicholas Lash said it was “disgraceful” that the Vatican devised the policy without even consulting Catholic bishops, much less Anglican ones.

Williams, for example – the spiritual leader of the worldwide Anglican Communion – wasn’t even informed of the change until right before it was announced.

Kasper referred to the criticism in his speech, saying that in the future issues of both conversion and ecumenism “should be undertaken in the greatest possible transparency, tactfulness and mutual esteem in order not to entail meaningless tensions with our ecumenical partners.”

One group that has cheered the new policy is the Traditional Anglican Communion (TAC), which split from the Anglican Communion in the early 1990s after the first women were ordained Anglican priests. The TAC, which has long sought to come under Rome’s wing, says it has 400,000 members in 41 countries, although only about half are regular churchgoers.

Already, TAC’s British province has voted to take Rome up on its invitation. TAC leader Archbishop John Hepworth has said he anticipates others will follow.

It remains to be seen how the new policy will affect Pope Benedict XVI’s planned trip to Britain next year. One thing is likely, however: The Vatican will surely hold out the upcoming beatification of the most famous Anglican convert, Cardinal John Henry Newman, as a symbol of bridge-building, since the 19th century theologian is a hero to many Anglicans and Catholics alike.