HARRISBURG - Gov. Corbett is expected to sign a controversial GOP-drafted plan for redrawing Pennsylvania's congressional boundaries, his office said Tuesday.

The proposed map for the state's 18 new districts was given final approval by the House on Tuesday, and the measure will be sent to Corbett's desk.

Critics say the proposed map, unveiled less than a week ago, is rife with gerrymandering and is a blatant attempt by Republicans to protect members of their own party.

Over the last few days, Democrats had tried to challenge the map's constitutionality and fairness to voters, but were unsuccessful. The majority of GOP legislators have defended it as constitutionally sound.

A new congressional map is required every decade to reflect shifts in population. Because Pennsylvania grew more slowly than the rest of the nation, it will lose a U.S. House seat, dropping to 18 in the 2012 election.

The party that controls the legislative chambers gets to draw the map. Republicans have majorities in both the House and Senate.

The proposed new district for Republican U.S. Rep. Patrick Meehan, in particular, has been held up as an example of Republicans taking care of their own.

Meehan has been considered one of the more vulnerable House members in 2012, representing a district carried by Democratic presidential candidates John Kerry in 2004 and Barack Obama in 2008. Democrats allege his new proposed district was drawn to excise Democratic areas in favor of more solidly Republican ones.

Also under the proposed map, U.S. Rep. Jim Gerlach's Sixth District would extend into Lebanon County; Easton would be separated from Allentown and Bethlehem in the Lehigh Valley; and the districts of U.S. Reps. Jason Altmire and Mark Critz, both Democrats, would be combined into a new 12th District in the western part of the state, which could force them to run against each other next year.

In other news, the legislature Monday sent Corbett a bill authorizing $1.7 billion in new borrowing to keep construction projects humming.

The legislation, known as the capital budget, includes $270 million for so-called - and, in recent years, controversial - redevelopment (or RCAP) projects. Those generally are economic development projects funded at the governor's discretion, although legislators draw up the wish list of projects they want funded.

The administration had warned lawmakers that if the bill was not approved by the end of the year, it would bring to a screeching halt thousands of construction projects around the state.

Contact staff writer Angela Couloumbis at 717-787-5934 or acouloumbis@phillynews.com.