Infighting within the Republican Party has so far dominated this year's General Assembly session, threatening Gov. Bob McDonnell's legacy-defining legislation with just two weeks remaining.

A looming gubernatorial election has made it unclear who controls the GOP -- McDonnell or the man Republicans have chosen to replace him, outspoken Attorney General Ken Cuccinelli. And there's Lt. Gov. Bill Bolling, too, whose public spat with Cuccinelli could escalate as the longtime party loyalist considers an independent bid for governor after dropping out of the Republican race in November.

Within the rank and file are delegates in Northern Virginia upset their caucus doesn't appreciate the transportation problems in the Beltway. GOP senators are angry that the Republican House speaker killed their redistricting plan. And conservative lawmakers bemoan that GOP leaders blocked their social bills this year.

All of it has become a major distraction for McDonnell as he has attempted to push a transportation funding overhaul that eliminates the 17.5-cent tax on a gallon of gas and raises the sales tax 0.8 cents to generate $3 billion for roads.

"Divisions that arose within the Republican Party that became controversial were unpredicted," said Bob Holsworth, a long-time Virginia political observer. "There's a question of what, if anything, can get done."

Tensions arose late last year when Bolling, McDonnell's handpicked successor, exited the governor's race and refused to back former rival Cuccinelli, instead threatening an independent run. McDonnell shifted support to Cuccinelli, who returned the favor by undercutting McDonnell's support in the Senate when he backed an alternative transportation bill. It failed, but McDonnell's plan did not even get a vote.

"You see every four years a bit of transition from the outgoing team to the incoming team," said Del. Rob Bell, a Charlottesville Republican running for attorney general. "I don't know if there's a magic date, but more and more of the tone will be set by [Cuccinelli] over time."

The Senate has another chance Wednesday to pass McDonnell's proposal, which narrowly passed the House last week with concern from Northern Virginia Republicans, who said it wasn't enough.

"We have to be treated better throughout this process," Del. Dave Albo, R-Springfield, said to his GOP colleagues outside the Beltway before reluctantly voting for it.

Senate Republicans put their political futures ahead of McDonnell's legacy when they passed a surprise redistricting proposal last month to give them an advantage in the 2015 elections. That angered McDonnell and Democrats, who vowed not to play ball on transportation. GOP House Speaker William Howell ruled last week that Senate Republicans were out of line, which immediately brought Democrats back to the negotiating table. But it soured relations with Howell's colleagues at the other end of the hall.

McDonnell has juggled his party's factions since taking office. He appeased moderate Republicans with a workmanlike approach to the budget and job creation and kept the base happy by quietly siding with conservatives in social battles. Under his watch, the party gained control of the Senate and extended its House majority.

"The more you win, the more voices you have," said McDonnell spokesman Tucker Martin. "It's not a problem, it's a natural result of political success."

But McDonnell's grip on those factions loosened since forcing lawmakers to take up such a bold transportation package with little warning, said Pat McSweeney, a former state GOP chairman.

"Bob has always had this division, but it may not have been quite apparent as it is now," McSweeney said. "When you face a divided group, you'll see them overtake the leader if he's not driving with a clear set of principles."