WASHINGTON (AP) — A rush of Republican retirements has positioned Democrats to pick up 20 or more seats in the House and transform what might otherwise be a march to modest gains on Election Day into a wave to a lopsided majority.

Across the country, GOP departures — many in districts the party has controlled for decades — have made an extraordinarily grim election year even tougher for Republicans.

If Democrats can capture a substantial number of the GOP’s 29 so-called open seats, they will have a stronger hand in the new Congress at moving an agenda that includes raising taxes on the wealthy and cutting them for the middle class, steering more federal benefits to low-income families and expanding health care coverage.

They also might solidify what could be a long-lasting House majority by gaining footholds in areas that have been off-limits to Democrats for a decade or longer. Democrats now enjoy a 235-199 majority in the House, with one vacancy. While no one envisions them building that to a veto-proof 270-seat majority this election, the closer they approach it the better chances their agenda will have, even should Republican John McCain win the White House.