Virginia Gov. Robert F. McDonnell warned his Republican brethren to take it slow this month as they took control of the state Senate.

“Don’t be arrogant, don’t overreach, don’t fight,” he told them.

If the flurry of legislation they’ve introduced is any indication, Virginia’s most conservative Republicans aren’t holding back.

They are pushing legislation to: wipe out corporate income taxes; mandate drug testing of welfare recipients; crack down on illegal immigrants; beef up gun rights, property rights, parental rights and fetal rights; roll back gay rights; and free the commonwealth from federal laws it doesn’t like.

Those are the highlights of an 80-bill agenda that the Virginia Conservative Caucus unveiled last week in Richmond. It’s an ambitious lineup, with twice the number of bills the group backed last year.

Many of those bills have come and gone before, sailing through the Republican-dominated House but dying in the Senate, where Democrats ruled for the past four years and moderate Republicans held sway before that. With the GOP now in control of the evenly split Senate, there’s hope among conservatives — and dread among liberals — that some of those measures will become law.

“It’s an optimistic time right now,” said Del. Ben L. Cline (R-Rockbridge), co-chairman of the conservative caucus. “We’ve got a conservative governor, a conservative House and a Senate with more conservatives in it. . . . I think on issues from taxes to social issues to immigration to public safety, conservatives are hoping to move the ball forward.”

Even as they seem to disregard McDonnell’s advice, Virginia’s most conservative legislators don’t expect to get everything on their wish list in this General Assembly session.

Democrats are still in a position to block them in certain areas — the budget, tax bills, constitutional amendments and judicial appointments — because Lt. Gov. Bill Bolling (R) lacks the authority to break tie votes on those matters. And on social issues such as guns and abortion, moderate Republicans could very well stand in their way.

McDonnell, who prides himself on working well with Republicans and Democrats alike, had hard-nosed political reasons for discouraging a pedal-to-the-metal, hard-right agenda. If conservatives go too far too quickly for voters in this swing state, there could be a backlash in this year’s U.S. Senate and presidential races in November, political observers say. It also could hurt McDonnell’s chances to wind up as somebody’s No. 2 on the Republican presidential ticket.

But for many conservatives who have been stymied for years by Democrats and moderate Republicans, there’s little inclination to wait.

“Legislation’s a lot like a football game; you move the ball down the field,” said Del. James P. Massie III (R-Henrico), who has a bill this year to provide tax credits to corporations that provide scholarships for poor students to attend private schools. “And I think we’re inside the five-yard line this year. And with the help of a couple more good Republicans like Dick Black over in the Senate. . . we’ll punch this thing across the goal.”

Black, a former delegate who moved up to the Senate this year, shares Massie’s enthusiasm for the conservative agenda. But he seems less certain of its prospects.

“There’s sort of a wait-and-see attitude,” Black (R-Leesburg) said. “I think we will make progress. I think the pro-life, pro-family groups are going to be pleased at the end of the session. I don’t think they’ll feel like they just had the victory at Gettysburg. I just think they’ll feel we’ve moved forward.”

Black, who as a delegate was one of the strongest anti-abortion voices in the General Assembly, has a seat this year on the Senate Education and Health Committee, where for years most anti-abortion legislation died.

Senate Republicans heavily stacked some crucial committees in their favor, scrapping a rule that committee seats reflect the party makeup of the Senate as a whole. But education and health comes as close as possible to mirroring the Senate’s 20-20 split, with eight Republicans (one of them chairman) and seven Democrats.

Some conservatives have grumbled that Senate Majority Leader Thomas K. Norment Jr. (R-James City), a moderate whom some conservatives considered replacing this year, did not do more to stack that committee, which has before it a number of abortion bills. One is the “personhood” bill, which seeks to define life as beginning at conception. Abortion-rights supporters warn that it could effectively outlaw the procedure as well as some forms of birth control, such as intrauterine devices. Another bill would require that any woman seeking an abortion be offered an ultrasound image of the fetus beforehand.

“We’re optimistic [about getting abortion bills out of committee], but you know it’s not as secure of a position as we had hoped at the margins,” Cline said. “There’s a single-vote margin on the committee.”

Adding to conservatives’ concerns: One Republican member of the committee, Sen. Harry B. Blevins (Chesapeake), is a moderate. Some conservatives privately refer to Blevins as “the Justice Kennedy of education and health,” comparing him to the frequent swing voter on the U.S. Supreme Court.

Blevins describes himself as “pro-life.” He voted last year in favor of new rules that regulate abortion clinics like hospitals instead of like doctors’ offices, as they had been. But he also said that unless and until the Supreme Court reverses Roe v. Wade, he is not inclined to support state measures to outlaw abortion.

“I think we have an obligation to uphold the law of the land,” he said. “Some people have this lock-step mentality. I’m not inclined to do that. ”

The conservative caucus also is pushing legislation that would: allow faith-based adoption agencies to refuse to place children with gay couples; lift a state requirement that schoolgirls get immunized against a sexually transmitted disease; and lift a one-gun-a month limit on handgun purchases. Another measure, called the repeal amendment, calls for amending the U.S. Constitution so that federal laws and regulations could be invalidated by agreement of two-thirds of state legislatures.

Legislation that could cost the state money could be a tough sell during tight budget times, some conservatives concede. But Cline, who sponsored a bill to eliminate the corporate income tax, said the measure could ultimately improve the state’s fiscal picture by attracting more businesses to Virginia.

The caucus has vowed to fight a number of bills, including those that would prohibit public employers from discriminating against employees on the basis of sexual orientation; provide in-state college tuition to undocumented immigrants; and impose a 20-cent plastic bag tax. One Republican, Del. David B. Albo of Fairfax, managed to make the caucus’s hit list with a bill about bingo. (It would raise maximum prizes to $1,000, up from the maximum now of $599.)

While Republicans are not confident of their success, Democrats aren’t feeling secure, either.

“We cannot become another Alabama or another Arizona. We represent something better,” said Del. Alfonso Lopez (D-Arlington), a member of the Virginia Progressive Caucus, referring to a bill that would empower state police to enforce immigration law.

Sen. George L. Barker (D-Fairfax) isn’t sure what to expect on the abortion bills he’ll consider as a member of the Education and Health Committee or on the conservative agenda overall.

“I think some of them will get through the committee,” he said. “How many will pass in the full Senate is definitely an open question. . . . We enter this year with a lot more uncertainty.”