We explained earlier this week why most conservatives would vote for the Ryan budget despite their complaints that it largely obtained balance in a relatively brief 10 years by including past tax increases.

That proved true Thursday, when only 10 Republicans voted “no” on the plan and decided against joining their party on one of its most unified votes. Here’s why they voted against House Budget Chairman Paul D. Ryan’s blueprint.

Six of the 10 said the Wisconsin Republican’s budget didn’t cut spending fast enough, while four said it cut spending too steeply or in the wrong areas.

Reps. Justin Amash of Michigan, Thomas Massie of Kentucky and Walter B. Jones of North Carolina — all “no” votes — are in the same ideological camp of libertarian-leaning Republicans urging far bolder spending cuts. Amash and Jones, who were thrown off their plum committee assignments in December, have become almost automatic “no” votes on spending bills that come out of the House. Massie has quickly joined their ranks.

Rep. Rick Crawford of Arkansas said in a statement that he voted against the budget because he wants “permanent spending controls,” not a “non-binding resolution” that can be “changed with each new Congress.”

Reps. Paul Broun and Phil Gingrey, both from Georgia, are eyeing the open Senate seat in their home state, which will require them to campaign against one another in a Republican primary. Two other potential contenders for the seat, Reps. Tom Price and Jack Kingston, voted for the budget.

On the other side of the ledger, Rep. J. Randy Forbes of Virginia said he couldn’t vote for the budget because it didn’t replace the sequester cuts that are hitting his military-heavy district hard.

Rep. Joe Heck of Nevada, who represents a swing district and is considered a target for defeat by Democrats in 2014, said the cuts “disproportionately affect” his home state.

West Virginia Rep. David B. McKinley was another “no” vote. He was also one of four members to vote against the budget last year, when he criticized it for cutting Medicare funding.

Rep. Chris Gibson did not immediately issue a statement on his vote, but is politically vulnerable in his marginal New York district and is one of the more liberal members of the GOP conference.

Generally speaking, the first six lawmakers are in safe districts where a primary challenge would be the biggest threat to them keeping the seats. The other four are more vulnerable districts, where those lawmakers could conceivably lose to a strong Democratic challenger.