Updated

August is the month when Republicans and their presumptive presidential nominee, Mitt Romney, will have their best chance yet to make their case to American voters. With Romney's announcement of a running mate in the coming days and the party's convention in Tampa at end of the month, the stakes are incredibly high for the GOP.

For Democrats and President Obama, August is a time to prepare for their own convention next month, to keep raising money, and do their best to muck up Romney's big moments.

Romney, just back from a bumpy trip to England, Israel and Poland, is expected to announce his running mate in the middle of the month after the end of the London Olympics on Aug. 12 and that will give the new team time to campaign together ahead of the GOP's convention kickoff on Aug. 27.

As the Olympics wind down, Romney will be out on the road on bus tours that will take him across several swing states, and ultimately around Florida before the Tampa convention. The week of Aug. 12 looks like prime time to meet Romney's running mate. Top contenders include Ohio Sen. Rob Portman, former Minnesota Gov. Tim Pawlenty, Virginia Gov. Bob McDonnell and Florida Sen. Marco Rubio.

Team Romney is doing everything possible to stoke speculation and anticipation about the running-mate pick: launching a smartphone app to let supporters get the news first, drawing attention to potential candidates as swing-state campaign surrogates, and using the moment as away to draw in new small-dollar donors.

The convention, though, will be the big moment for Romney and his running mate. It's one thing to give a stump speech outside of a bus, but quite another to deliver an address to thousands in a convention hall and millions more at home. And while Romney's speech to close the convention will set the tone for the rest of his campaign, the vice presidential nominee's speech will be a make-or-break moment for the Republican ticket.

The convention is expected to offer some other dramatic moments. Libertarian-leaning backers of presidential contender Rep. Ron Paul, R-Texas, and socially conservative supporters of onetime candidate former Sen. Rick Santorum, are all hoping to have their voices heard and to influence the party's platform. The choreography of speaking slots and campaign language will all be part of keeping the conservative coalition together for the Republican National Committee.

The president, meanwhile, will be keeping up his steady pace of swing-state campaign stops and high-dollar fundraisers. With his campaign burning through cash at a huge rate, Obama needs lots of cash to keep up the barrage of attack ads aimed at Romney's personal finances and business career.

The Obama campaign has scheduled a massive fundraising effort for the president's birthday on Aug. 4. Not only will big donors get a chance, but small-dollar donors can win a chance to be at the birthday party through an online raffle.

Obama will be working hard to reinforce the negative image of Romney, as greedy and uncaring - an effort that began in the spring. As Romney soaks up the spotlight this month, Obama will be using his still-considerable cash advantage and the presidential bully pulpit to make that light as harsh as possible.

One respite from the intensely negative campaign will come in the week of Aug. 20, when evangelical pastor and best-selling author Rick Warren is expected to host a forum for the two candidates at his Saddleback Church in Orange County, Calif. This should be an opportunity for Obama to show his softer side and discuss his troubled youth and family life. The forum could prove challenging for Romney, who is typically more at ease discussing economic policy than emotions.

With only three months to go in the presidential race, the candidates need to make every moment in August count.